diff --git a/pygmt/accessors.py b/pygmt/accessors.py
index ec73f69238f..711778b7d11 100644
--- a/pygmt/accessors.py
+++ b/pygmt/accessors.py
@@ -6,6 +6,7 @@
 from pathlib import Path
 
 import xarray as xr
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.src.grdinfo import grdinfo
 
@@ -15,110 +16,122 @@ class GMTDataArrayAccessor:
     """
     GMT accessor for :class:`xarray.DataArray`.
 
-    The accessor extends :class:`xarray.DataArray` to store GMT-specific
-    properties about grids, which are important for PyGMT to correctly process
-    and plot the grids.
+    The *gmt* accessor extends :class:`xarray.DataArray` to store GMT-specific
+    properties for grids, which are important for PyGMT to correctly process and plot
+    the grids. The *gmt* accessor contains the following properties:
 
-    Notes
-    -----
-
-    Due to the limitations of xarray accessors, the GMT accessors are created
-    once per :class:`xarray.DataArray` instance. You may lose these
-    GMT-specific properties when manipulating grids (e.g., arithmetic and slice
-    operations) or when accessing a :class:`xarray.DataArray` from a
-    :class:`xarray.Dataset`. In these cases, you need to manually set these
-    properties before passing the grid to PyGMT.
+    - ``registration``: Grid registration type :class:`pygmt.enums.GridRegistration`.
+    - ``gtype``: Grid coordinate system type :class:`pygmt.enums.GridType`.
 
     Examples
     --------
-
-    For GMT's built-in remote datasets, these GMT-specific properties are
-    automatically determined and you can access them as follows:
+    For GMT's built-in remote datasets, these GMT-specific properties are automatically
+    determined and you can access them as follows:
 
     >>> from pygmt.datasets import load_earth_relief
     >>> # Use the global Earth relief grid with 1 degree spacing
     >>> grid = load_earth_relief(resolution="01d", registration="pixel")
-    >>> # See if grid uses Gridline (0) or Pixel (1) registration
+    >>> # See if grid uses Gridline or Pixel registration
     >>> grid.gmt.registration
-    1
-    >>> # See if grid uses Cartesian (0) or Geographic (1) coordinate system
+    <GridRegistration.PIXEL: 1>
+    >>> # See if grid is in Cartesian or Geographic coordinate system
     >>> grid.gmt.gtype
-    1
+    <GridType.GEOGRAPHIC: 1>
 
-    For :class:`xarray.DataArray` grids created by yourself, grid properties
-    ``registration`` and ``gtype`` default to 0 (i.e., a gridline-registered,
-    Cartesian grid). You need to set the correct properties before
-    passing it to PyGMT functions:
+    For :class:`xarray.DataArray` grids created by yourself, ``registration`` and
+    ``gtype`` default to ``GridRegistration.GRIDLINE`` and ``GridType.CARTESIAN`` (i.e.,
+    a gridline-registered, Cartesian grid). You need to set the correct properties
+    before passing it to PyGMT functions:
 
     >>> import numpy as np
-    >>> import pygmt
     >>> import xarray as xr
-    >>> # create a DataArray in gridline coordinates of sin(lon) * cos(lat)
+    >>> import pygmt
+    >>> from pygmt.enums import GridRegistration, GridType
+    >>> # Create a DataArray in gridline coordinates of sin(lon) * cos(lat)
     >>> interval = 2.5
     >>> lat = np.arange(90, -90 - interval, -interval)
     >>> lon = np.arange(0, 360 + interval, interval)
     >>> longrid, latgrid = np.meshgrid(lon, lat)
     >>> data = np.sin(np.deg2rad(longrid)) * np.cos(np.deg2rad(latgrid))
     >>> grid = xr.DataArray(data, coords=[("latitude", lat), ("longitude", lon)])
-    >>> # default to a gridline-registered Cartesian grid
-    >>> grid.gmt.registration, grid.gmt.gtype
-    (0, 0)
-    >>> # set it to a gridline-registered geographic grid
-    >>> grid.gmt.registration = 0
-    >>> grid.gmt.gtype = 1
-    >>> grid.gmt.registration, grid.gmt.gtype
-    (0, 1)
-
-    Note that the accessors are created once per :class:`xarray.DataArray`
-    instance, so you may lose these GMT-specific properties after manipulating
-    your grid.
+    >>> # Default to a gridline-registered Cartesian grid
+    >>> grid.gmt.registration
+    <GridRegistration.GRIDLINE: 0>
+    >>> grid.gmt.gtype
+    <GridType.CARTESIAN: 0>
+    >>> # Manually set it to a gridline-registered geographic grid
+    >>> grid.gmt.registration = GridRegistration.GRIDLINE
+    >>> grid.gmt.gtype = GridType.GEOGRAPHIC
+    >>> grid.gmt.registration
+    <GridRegistration.GRIDLINE: 0>
+    >>> grid.gmt.gtype
+    <GridType.GEOGRAPHIC: 1>
+
+    Notes
+    -----
+    Due to the limitations of xarray accessors, the GMT accessors are created once per
+    :class:`xarray.DataArray` instance. You may lose these GMT-specific properties when
+    manipulating grids (e.g., arithmetic and slice operations) or when accessing a
+    :class:`xarray.DataArray` from a :class:`xarray.Dataset`. In these cases, you need
+    to manually set these properties before passing the grid to PyGMT.
 
     Inplace assignment operators like ``*=`` don't create new instances, so the
     properties are still kept:
 
     >>> grid *= 2.0
-    >>> grid.gmt.registration, grid.gmt.gtype
-    (0, 1)
+    >>> grid.gmt.registration
+    <GridRegistration.GRIDLINE: 0>
+    >>> grid.gmt.gtype
+    <GridType.GEOGRAPHIC: 1>
 
-    Other grid operations (e.g., arithmetic or slice operations) create new
-    instances, so the properties will be lost:
+    Other grid operations (e.g., arithmetic or slice operations) create new instances,
+    so the properties will be lost:
 
     >>> # grid2 is a slice of the original grid
     >>> grid2 = grid[0:30, 50:80]
-    >>> # properties are reset to the default values for new instance
-    >>> grid2.gmt.registration, grid2.gmt.gtype
-    (0, 0)
-    >>> # need to set these properties before passing the grid to PyGMT
+    >>> # Properties are reset to the default values for new instance
+    >>> grid2.gmt.registration
+    <GridRegistration.GRIDLINE: 0>
+    >>> grid2.gmt.gtype
+    <GridType.CARTESIAN: 0>
+    >>> # Need to set these properties before passing the grid to PyGMT
     >>> grid2.gmt.registration = grid.gmt.registration
     >>> grid2.gmt.gtype = grid.gmt.gtype
-    >>> grid2.gmt.registration, grid2.gmt.gtype
-    (0, 1)
+    >>> grid2.gmt.registration
+    <GridRegistration.GRIDLINE: 0>
+    >>> grid2.gmt.gtype
+    <GridType.GEOGRAPHIC: 1>
 
-    Accessing a :class:`xarray.DataArray` from a :class:`xarray.Dataset` always
-    creates new instances, so these properties are always lost. The workaround
-    is to assign the :class:`xarray.DataArray` into a variable:
+    Accessing a :class:`xarray.DataArray` from a :class:`xarray.Dataset` always creates
+    new instances, so these properties are always lost. The workaround is to assign the
+    :class:`xarray.DataArray` into a variable:
 
     >>> ds = xr.Dataset({"zval": grid})
+    >>> ds.zval.gmt.registration
+    <GridRegistration.GRIDLINE: 0>
+    >>> ds.zval.gmt.gtype
+    <GridType.CARTESIAN: 0>
+    >>> # Manually set these properties won't work as expected
+    >>> ds.zval.gmt.registration = GridRegistration.GRIDLINE
+    >>> ds.zval.gmt.gtype = GridType.GEOGRAPHIC
     >>> ds.zval.gmt.registration, ds.zval.gmt.gtype
-    (0, 0)
-    >>> # manually set these properties won't work as expected
-    >>> ds.zval.gmt.registration, ds.zval.gmt.gtype = 0, 1
-    >>> ds.zval.gmt.registration, ds.zval.gmt.gtype
-    (0, 0)
+    (<GridRegistration.GRIDLINE: 0>, <GridType.CARTESIAN: 0>)
     >>> # workaround: assign the DataArray into a variable
     >>> zval = ds.zval
     >>> zval.gmt.registration, zval.gmt.gtype
-    (0, 0)
-    >>> zval.gmt.registration, zval.gmt.gtype = 0, 1
+    (<GridRegistration.GRIDLINE: 0>, <GridType.CARTESIAN: 0>)
+    >>> zval.gmt.registration = GridRegistration.GRIDLINE
+    >>> zval.gmt.gtype = GridType.GEOGRAPHIC
     >>> zval.gmt.registration, zval.gmt.gtype
-    (0, 1)
+    (<GridRegistration.GRIDLINE: 0>, <GridType.GEOGRAPHIC: 1>)
     """
 
     def __init__(self, xarray_obj):
         self._obj = xarray_obj
+
         # Default to Gridline registration and Cartesian grid type
-        self._registration = 0
-        self._gtype = 0
+        self._registration = GridRegistration.GRIDLINE
+        self._gtype = GridType.CARTESIAN
 
         # If the source file exists, get grid registration and grid type from the last
         # two columns of the shortened summary information of grdinfo.
@@ -131,33 +144,35 @@ def __init__(self, xarray_obj):
     @property
     def registration(self):
         """
-        Registration type of the grid, either 0 (Gridline) or 1 (Pixel).
+        Grid registration type :class:`pygmt.enums.GridRegistration`.
         """
         return self._registration
 
     @registration.setter
     def registration(self, value):
-        if value not in {0, 1}:
+        # TODO(Python>=3.12): Simplify to `if value not in GridRegistration`.
+        if value not in GridRegistration.__members__.values():
             msg = (
-                f"Invalid grid registration value: {value}, should be either "
-                "0 for Gridline registration or 1 for Pixel registration."
+                f"Invalid grid registration: '{value}'. Should be either "
+                "GridRegistration.GRIDLINE (0) or GridRegistration.PIXEL (1)."
             )
             raise GMTInvalidInput(msg)
-        self._registration = value
+        self._registration = GridRegistration(value)
 
     @property
     def gtype(self):
         """
-        Coordinate system type of the grid, either 0 (Cartesian) or 1 (Geographic).
+        Grid coordinate system type :class:`pygmt.enums.GridType`.
         """
         return self._gtype
 
     @gtype.setter
     def gtype(self, value):
-        if value not in {0, 1}:
+        # TODO(Python>=3.12): Simplify to `if value not in GridType`.
+        if value not in GridType.__members__.values():
             msg = (
-                f"Invalid coordinate system type: {value}, should be "
-                "either 0 for Cartesian or 1 for Geographic."
+                f"Invalid grid coordinate system type: '{value}'. "
+                "Should be either GridType.CARTESIAN (0) or GridType.GEOGRAPHIC (1)."
             )
             raise GMTInvalidInput(msg)
-        self._gtype = value
+        self._gtype = GridType(value)
diff --git a/pygmt/datatypes/grid.py b/pygmt/datatypes/grid.py
index 18ad679aeef..8b4426b01c5 100644
--- a/pygmt/datatypes/grid.py
+++ b/pygmt/datatypes/grid.py
@@ -165,7 +165,7 @@ def to_dataarray(self) -> xr.DataArray:
             axis:           Y
             actual_range:   [-24. -10.]
         >>> da.gmt.registration, da.gmt.gtype
-        (1, 1)
+        (<GridRegistration.PIXEL: 1>, <GridType.GEOGRAPHIC: 1>)
         """
         # The grid header
         header = self.header.contents
diff --git a/pygmt/datatypes/image.py b/pygmt/datatypes/image.py
index 8534bfaacb3..3cd3a106bc1 100644
--- a/pygmt/datatypes/image.py
+++ b/pygmt/datatypes/image.py
@@ -166,7 +166,7 @@ def to_dataarray(self) -> xr.DataArray:
             axis:          Y
             actual_range:  [-90.  90.]
         >>> da.gmt.registration, da.gmt.gtype
-        (1, 1)
+        (<GridRegistration.PIXEL: 1>, <GridType.GEOGRAPHIC: 1>)
         """
         # The image header
         header = self.header.contents
diff --git a/pygmt/src/tilemap.py b/pygmt/src/tilemap.py
index e61cd82e868..0748c83a2c9 100644
--- a/pygmt/src/tilemap.py
+++ b/pygmt/src/tilemap.py
@@ -6,6 +6,7 @@
 
 from pygmt.clib import Session
 from pygmt.datasets.tile_map import load_tile_map
+from pygmt.enums import GridType
 from pygmt.helpers import build_arg_list, fmt_docstring, kwargs_to_strings, use_alias
 
 try:
@@ -121,7 +122,7 @@ def tilemap(
         zoom_adjust=zoom_adjust,
     )
     if lonlat:
-        raster.gmt.gtype = 1  # Set to geographic type
+        raster.gmt.gtype = GridType.GEOGRAPHIC
 
     # Only set region if no_clip is None or False, so that plot is clipped to exact
     # bounding box region
diff --git a/pygmt/tests/test_accessor.py b/pygmt/tests/test_accessor.py
index 07ece609b69..7931c39313d 100644
--- a/pygmt/tests/test_accessor.py
+++ b/pygmt/tests/test_accessor.py
@@ -11,66 +11,96 @@
 from pygmt import which
 from pygmt.clib import __gmt_version__
 from pygmt.datasets import load_earth_relief
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 
 
 def test_accessor_gridline_cartesian():
     """
-    Check that a grid returns a registration value of 0 when Gridline registered, and a
-    gtype value of 1 when using Geographic coordinates.
+    Check that the accessor returns the correct registration and gtype values for a
+    Cartesian, gridline-registered grid.
     """
     fname = which(fname="@test.dat.nc", download="a")
-    grid = xr.open_dataarray(fname)
-    assert grid.gmt.registration == 0  # gridline registration
-    assert grid.gmt.gtype == 0  # cartesian coordinate type
+    grid = xr.open_dataarray(fname, engine="netcdf4")
+    assert grid.gmt.registration == GridRegistration.GRIDLINE
+    assert grid.gmt.gtype == GridType.CARTESIAN
 
 
 def test_accessor_pixel_geographic():
     """
-    Check that a grid returns a registration value of 1 when Pixel registered, and a
-    gtype value of 0 when using Cartesian coordinates.
+    Check that the accessor returns the correct registration and gtype values for a
+    geographic, pixel-registered grid.
     """
     fname = which(fname="@earth_relief_01d_p", download="a")
     grid = xr.open_dataarray(fname, engine="netcdf4")
-    assert grid.gmt.registration == 1  # pixel registration
-    assert grid.gmt.gtype == 1  # geographic coordinate type
+    assert grid.gmt.registration == GridRegistration.PIXEL
+    assert grid.gmt.gtype == GridType.GEOGRAPHIC
 
 
-def test_accessor_set_pixel_registration():
+def test_accessor_set_registration():
     """
-    Check that we can set a grid to be Pixel registered with a registration value of 1.
+    Check that we can set the registration of a grid.
     """
     grid = xr.DataArray(data=[[0.1, 0.2], [0.3, 0.4]])
-    assert grid.gmt.registration == 0  # default to gridline registration
-    grid.gmt.registration = 1  # set to pixel registration
-    assert grid.gmt.registration == 1  # ensure changed to pixel registration
+    # Default to gridline registration
+    assert grid.gmt.registration == GridRegistration.GRIDLINE == 0
+
+    # Set the registration to pixel
+    grid.gmt.registration = GridRegistration.PIXEL
+    assert grid.gmt.registration == GridRegistration.PIXEL == 1
+
+    # Set the registration to gridline
+    grid.gmt.registration = GridRegistration.GRIDLINE
+    assert grid.gmt.registration == GridRegistration.GRIDLINE == 0
+
+    # Set the registration to pixel but using a numerical value
+    grid.gmt.registration = 1
+    assert grid.gmt.registration == GridRegistration.PIXEL == 1
+
+    # Set the registration to gridline but using a numerical value
+    grid.gmt.registration = 0
+    assert grid.gmt.registration == GridRegistration.GRIDLINE == 0
 
 
 @pytest.mark.benchmark
-def test_accessor_set_geographic_cartesian_roundtrip():
+def test_accessor_set_gtype():
     """
-    Check that we can set a grid to switch between the default Cartesian coordinate type
-    using a gtype of 1, set it to Geographic 0, and then back to Cartesian again 1.
+    Check that we can set the gtype of a grid.
     """
     grid = xr.DataArray(data=[[0.1, 0.2], [0.3, 0.4]])
-    assert grid.gmt.gtype == 0  # default to cartesian coordinate type
-    grid.gmt.gtype = 1  # set to geographic type
-    assert grid.gmt.gtype == 1  # ensure changed to geographic coordinate type
-    grid.gmt.gtype = 0  # set back to cartesian type
-    assert grid.gmt.gtype == 0  # ensure changed to cartesian coordinate type
+    assert grid.gmt.gtype == GridType.CARTESIAN == 0  # Default gtype
+
+    # Set the gtype to geographic
+    grid.gmt.gtype = GridType.GEOGRAPHIC
+    assert grid.gmt.gtype == GridType.GEOGRAPHIC == 1
 
+    # Set the gtype to Cartesian
+    grid.gmt.gtype = GridType.CARTESIAN
+    assert grid.gmt.gtype == GridType.CARTESIAN == 0
 
-def test_accessor_set_non_boolean():
+    # Set the gtype to geographic but using a numerical value
+    grid.gmt.gtype = 1
+    assert grid.gmt.gtype == GridType.GEOGRAPHIC == 1
+
+    # Set the gtype to Cartesian but using a numerical value
+    grid.gmt.gtype = 0
+    assert grid.gmt.gtype == GridType.CARTESIAN == 0
+
+
+def test_accessor_set_invalid_registration_and_gtype():
     """
-    Check that setting non boolean values on registration and gtype do not work.
+    Check that setting invalid values on registration and gtype do not work.
     """
     grid = xr.DataArray(data=[[0.1, 0.2], [0.3, 0.4]])
 
     with pytest.raises(GMTInvalidInput):
         grid.gmt.registration = "2"
-
+    with pytest.raises(GMTInvalidInput):
+        grid.gmt.registration = "pixel"
     with pytest.raises(GMTInvalidInput):
         grid.gmt.gtype = 2
+    with pytest.raises(GMTInvalidInput):
+        grid.gmt.gtype = "geographic"
 
 
 # TODO(GMT>=6.5.0): Remove the xfail marker for GMT>=6.5.0.
@@ -94,8 +124,8 @@ def test_accessor_sliced_datacube():
         with xr.open_dataset(fname) as dataset:
             grid = dataset.sel(level=500, month=1, drop=True).z
 
-        assert grid.gmt.registration == 0  # gridline registration
-        assert grid.gmt.gtype == 1  # geographic coordinate type
+        assert grid.gmt.registration == GridRegistration.GRIDLINE
+        assert grid.gmt.gtype == GridType.GEOGRAPHIC
     finally:
         Path(fname).unlink()
 
@@ -105,24 +135,24 @@ def test_accessor_grid_source_file_not_exist():
     Check that the accessor fallbacks to the default registration and gtype when the
     grid source file (i.e., grid.encoding["source"]) doesn't exist.
     """
-    # Load the 05m earth relief grid, which is stored as tiles
+    # Load the 05m earth relief grid, which is stored as tiles.
     grid = load_earth_relief(
         resolution="05m", region=[0, 5, -5, 5], registration="pixel"
     )
-    # Registration and gtype are correct
-    assert grid.gmt.registration == 1
-    assert grid.gmt.gtype == 1
+    # Registration and gtype are correct.
+    assert grid.gmt.registration == GridRegistration.PIXEL
+    assert grid.gmt.gtype == GridType.GEOGRAPHIC
     # The source grid file is undefined.
     assert grid.encoding.get("source") is None
 
-    # For a sliced grid, fallback to default registration and gtype,
-    # because the source grid file doesn't exist.
+    # For a sliced grid, fallback to default registration and gtype, because the source
+    # grid file doesn't exist.
     sliced_grid = grid[1:3, 1:3]
-    assert sliced_grid.gmt.registration == 0
-    assert sliced_grid.gmt.gtype == 0
-
-    # Still possible to manually set registration and gtype
-    sliced_grid.gmt.registration = 1
-    sliced_grid.gmt.gtype = 1
-    assert sliced_grid.gmt.registration == 1
-    assert sliced_grid.gmt.gtype == 1
+    assert sliced_grid.gmt.registration == GridRegistration.GRIDLINE
+    assert sliced_grid.gmt.gtype == GridType.CARTESIAN
+
+    # Still possible to manually set registration and gtype.
+    sliced_grid.gmt.registration = GridRegistration.PIXEL
+    sliced_grid.gmt.gtype = GridType.GEOGRAPHIC
+    assert sliced_grid.gmt.registration == GridRegistration.PIXEL
+    assert sliced_grid.gmt.gtype == GridType.GEOGRAPHIC
diff --git a/pygmt/tests/test_binstats.py b/pygmt/tests/test_binstats.py
index b8a1a39e8ad..eeaa22020d5 100644
--- a/pygmt/tests/test_binstats.py
+++ b/pygmt/tests/test_binstats.py
@@ -7,6 +7,7 @@
 import numpy.testing as npt
 import pytest
 from pygmt import binstats
+from pygmt.enums import GridRegistration, GridType
 from pygmt.helpers import GMTTempFile
 
 
@@ -42,8 +43,8 @@ def test_binstats_no_outgrid():
         region="g",
     )
     assert temp_grid.dims == ("y", "x")
-    assert temp_grid.gmt.gtype == 0  # Cartesian grid
-    assert temp_grid.gmt.registration == 0  # Gridline registration
+    assert temp_grid.gmt.gtype == GridType.CARTESIAN
+    assert temp_grid.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(temp_grid.max(), 35971536)
     npt.assert_allclose(temp_grid.min(), 53)
     npt.assert_allclose(temp_grid.median(), 1232714.5)
diff --git a/pygmt/tests/test_datasets_earth_age.py b/pygmt/tests/test_datasets_earth_age.py
index 67ade3dd3d9..3407ac0776a 100644
--- a/pygmt/tests/test_datasets_earth_age.py
+++ b/pygmt/tests/test_datasets_earth_age.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_earth_age
+from pygmt.enums import GridRegistration
 
 
 def test_earth_age_01d():
@@ -18,7 +19,7 @@ def test_earth_age_01d():
     assert data.attrs["units"] == "Myr"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), 0.37, atol=0.01)
@@ -31,7 +32,7 @@ def test_earth_age_01d_with_region():
     """
     data = load_earth_age(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), 11.13, atol=0.01)
@@ -45,7 +46,7 @@ def test_earth_age_01m_default_registration():
     """
     data = load_earth_age(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_earth_day.py b/pygmt/tests/test_datasets_earth_day.py
index f04d7f7f970..f04269135f8 100644
--- a/pygmt/tests/test_datasets_earth_day.py
+++ b/pygmt/tests/test_datasets_earth_day.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_blue_marble
+from pygmt.enums import GridRegistration, GridType
 
 
 def test_blue_marble_01d():
@@ -18,8 +19,8 @@ def test_blue_marble_01d():
     assert data.attrs["description"] == "NASA Day Images"
     assert data.shape == (3, 180, 360)
     assert data.dtype == "uint8"
-    assert data.gmt.registration == 1
-    assert data.gmt.gtype == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.gtype == GridType.GEOGRAPHIC
     npt.assert_allclose(data.y, np.arange(89.5, -90.5, -1))
     npt.assert_allclose(data.x, np.arange(-179.5, 180.5, 1))
     npt.assert_allclose(data.min(), 10, atol=1)
@@ -33,8 +34,8 @@ def test_blue_marble_01d_with_region():
     data = load_blue_marble(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (3, 10, 20)
     assert data.dtype == "uint8"
-    assert data.gmt.registration == 1
-    assert data.gmt.gtype == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.gtype == GridType.GEOGRAPHIC
     npt.assert_allclose(data.y, np.arange(4.5, -5.5, -1))
     npt.assert_allclose(data.x, np.arange(-9.5, 10.5, 1))
     npt.assert_allclose(data.min(), 10, atol=1)
diff --git a/pygmt/tests/test_datasets_earth_deflection.py b/pygmt/tests/test_datasets_earth_deflection.py
index 9118779a379..a30eab07902 100644
--- a/pygmt/tests/test_datasets_earth_deflection.py
+++ b/pygmt/tests/test_datasets_earth_deflection.py
@@ -6,6 +6,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_earth_deflection
+from pygmt.enums import GridRegistration
 
 
 def test_earth_edefl_01d():
@@ -19,7 +20,7 @@ def test_earth_edefl_01d():
     assert data.attrs["units"] == "micro-radians"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -142.64, atol=0.04)
@@ -32,7 +33,7 @@ def test_earth_edefl_01d_with_region():
     """
     data = load_earth_deflection(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -28.92, atol=0.04)
@@ -46,7 +47,7 @@ def test_earth_edefl_01m_default_registration():
     """
     data = load_earth_deflection(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (120, 60)
-    assert data.gmt.registration == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.008333333)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.991666666)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.99166666)
@@ -66,7 +67,7 @@ def test_earth_ndefl_01d():
     assert data.attrs["units"] == "micro-radians"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -214.8, atol=0.04)
@@ -81,7 +82,7 @@ def test_earth_ndefl_01d_with_region():
         resolution="01d", region=[-10, 10, -5, 5], component="north"
     )
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -48.08, atol=0.04)
@@ -97,7 +98,7 @@ def test_earth_ndefl_01m_default_registration():
         resolution="01m", region=[-10, -9, 3, 5], component="north"
     )
     assert data.shape == (120, 60)
-    assert data.gmt.registration == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.008333333)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.991666666)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.99166666)
diff --git a/pygmt/tests/test_datasets_earth_dist.py b/pygmt/tests/test_datasets_earth_dist.py
index a5f61a0b5f2..78c2b24c988 100644
--- a/pygmt/tests/test_datasets_earth_dist.py
+++ b/pygmt/tests/test_datasets_earth_dist.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_earth_dist
+from pygmt.enums import GridRegistration
 
 
 def test_earth_dist_01d():
@@ -17,7 +18,7 @@ def test_earth_dist_01d():
     assert data.attrs["units"] == "kilometers"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -2655.7, atol=0.01)
@@ -30,7 +31,7 @@ def test_earth_dist_01d_with_region():
     """
     data = load_earth_dist(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -1081.94, atol=0.01)
@@ -44,7 +45,7 @@ def test_earth_dist_01m_default_registration():
     """
     data = load_earth_dist(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_earth_free_air_anomaly.py b/pygmt/tests/test_datasets_earth_free_air_anomaly.py
index 7ce5fc2662c..a60c1fec2e6 100644
--- a/pygmt/tests/test_datasets_earth_free_air_anomaly.py
+++ b/pygmt/tests/test_datasets_earth_free_air_anomaly.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_earth_free_air_anomaly
+from pygmt.enums import GridRegistration
 
 
 def test_earth_faa_01d():
@@ -18,7 +19,7 @@ def test_earth_faa_01d():
     assert data.attrs["units"] == "mGal"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -188.85, atol=0.025)
@@ -31,7 +32,7 @@ def test_earth_faa_01d_with_region():
     """
     data = load_earth_free_air_anomaly(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -36.125, atol=0.025)
@@ -45,7 +46,7 @@ def test_earth_faa_01m_default_registration():
     """
     data = load_earth_free_air_anomaly(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (120, 60)
-    assert data.gmt.registration == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.008333333)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.991666666)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.99166666)
@@ -65,7 +66,7 @@ def test_earth_faaerror_01d():
     assert data.attrs["units"] == "mGal"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), 0.0, atol=0.04)
@@ -80,7 +81,7 @@ def test_earth_faaerror_01d_with_region():
         resolution="01d", region=[-10, 10, -5, 5], uncertainty=True
     )
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), 0.72, atol=0.04)
@@ -96,7 +97,7 @@ def test_earth_faaerror_01m_default_registration():
         resolution="01m", region=[-10, -9, 3, 5], uncertainty=True
     )
     assert data.shape == (120, 60)
-    assert data.gmt.registration == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.008333333)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.991666666)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.99166666)
diff --git a/pygmt/tests/test_datasets_earth_geoid.py b/pygmt/tests/test_datasets_earth_geoid.py
index af72969b032..bb7f09102d9 100644
--- a/pygmt/tests/test_datasets_earth_geoid.py
+++ b/pygmt/tests/test_datasets_earth_geoid.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_earth_geoid
+from pygmt.enums import GridRegistration
 
 
 def test_earth_geoid_01d():
@@ -18,7 +19,7 @@ def test_earth_geoid_01d():
     assert data.attrs["units"] == "meters"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -106.06, atol=0.01)
@@ -31,7 +32,7 @@ def test_earth_geoid_01d_with_region():
     """
     data = load_earth_geoid(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), 5.57, atol=0.01)
@@ -45,7 +46,7 @@ def test_earth_geoid_01m_default_registration():
     """
     data = load_earth_geoid(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_earth_magnetic_anomaly.py b/pygmt/tests/test_datasets_earth_magnetic_anomaly.py
index 65e1a57601c..e580e565094 100644
--- a/pygmt/tests/test_datasets_earth_magnetic_anomaly.py
+++ b/pygmt/tests/test_datasets_earth_magnetic_anomaly.py
@@ -6,6 +6,7 @@
 import numpy.testing as npt
 import pytest
 from pygmt.datasets import load_earth_magnetic_anomaly
+from pygmt.enums import GridRegistration
 from pygmt.exceptions import GMTInvalidInput
 
 
@@ -20,7 +21,7 @@ def test_earth_mag_01d():
     assert data.attrs["units"] == "nT"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -336.2, atol=0.2)
@@ -33,7 +34,7 @@ def test_earth_mag_01d_with_region():
     """
     data = load_earth_magnetic_anomaly(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -54.4, atol=0.2)
@@ -47,7 +48,7 @@ def test_earth_mag_02m_default_registration():
     """
     data = load_earth_magnetic_anomaly(resolution="02m", region=[-10, -9, 3, 5])
     assert data.shape == (60, 30)
-    assert data.gmt.registration == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.016666667)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.983333333)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.98333333)
@@ -67,7 +68,7 @@ def test_earth_mag4km_01d():
     assert data.attrs["units"] == "nT"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -436.8, atol=0.2)
@@ -102,7 +103,7 @@ def test_earth_mag4km_02m_default_registration():
         data_source="emag2_4km",
     )
     assert data.shape == (60, 90)
-    assert data.gmt.registration == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 4.01666667)
     npt.assert_allclose(data.coords["lat"].data.max(), 5.98333333)
     npt.assert_allclose(data.coords["lon"].data.min(), -114.98333333)
@@ -154,7 +155,7 @@ def test_earth_mag_03m_wdmam_with_region():
     data = load_earth_magnetic_anomaly(
         resolution="03m", region=[10, 13, -60, -58], data_source="wdmam"
     )
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.shape == (41, 61)
     assert data.lat.min() == -60
     assert data.lat.max() == -58
diff --git a/pygmt/tests/test_datasets_earth_mask.py b/pygmt/tests/test_datasets_earth_mask.py
index c449e1a79a7..3e33ab1172b 100644
--- a/pygmt/tests/test_datasets_earth_mask.py
+++ b/pygmt/tests/test_datasets_earth_mask.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_earth_mask
+from pygmt.enums import GridRegistration, GridType
 
 
 def test_earth_mask_01d():
@@ -16,8 +17,8 @@ def test_earth_mask_01d():
     assert data.attrs["description"] == "GSHHG Earth mask"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
-    assert data.gmt.gtype == 1
+    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.gtype == GridType.GEOGRAPHIC
     assert data.dtype == "int8"
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
@@ -32,8 +33,8 @@ def test_earth_mask_01d_with_region():
     """
     data = load_earth_mask(resolution="01d", region=[-7, 4, 13, 19])
     assert data.shape == (7, 12)
-    assert data.gmt.registration == 0
-    assert data.gmt.gtype == 1
+    assert data.gmt.registration == GridRegistration.GRIDLINE
+    assert data.gmt.gtype == GridType.GEOGRAPHIC
     assert data.dtype == "int8"
     npt.assert_allclose(data.lat, np.arange(13, 20, 1))
     npt.assert_allclose(data.lon, np.arange(-7, 5, 1))
diff --git a/pygmt/tests/test_datasets_earth_mean_sea_surface.py b/pygmt/tests/test_datasets_earth_mean_sea_surface.py
index 84b2b7123cc..7206cbf911f 100644
--- a/pygmt/tests/test_datasets_earth_mean_sea_surface.py
+++ b/pygmt/tests/test_datasets_earth_mean_sea_surface.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_earth_mean_sea_surface
+from pygmt.enums import GridRegistration
 
 
 def test_earth_mss_01d():
@@ -17,7 +18,7 @@ def test_earth_mss_01d():
     assert data.attrs["units"] == "meters"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -104.71, atol=0.01)
@@ -30,7 +31,7 @@ def test_earth_mss_01d_with_region():
     """
     data = load_earth_mean_sea_surface(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), 6.53, atol=0.01)
@@ -44,7 +45,7 @@ def test_earth_mss_01m_default_registration():
     """
     data = load_earth_mean_sea_surface(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_earth_night.py b/pygmt/tests/test_datasets_earth_night.py
index dd6b3374033..0865feaa1e8 100644
--- a/pygmt/tests/test_datasets_earth_night.py
+++ b/pygmt/tests/test_datasets_earth_night.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_black_marble
+from pygmt.enums import GridRegistration, GridType
 
 
 def test_black_marble_01d():
@@ -18,8 +19,8 @@ def test_black_marble_01d():
     assert data.attrs["description"] == "NASA Night Images"
     assert data.shape == (3, 180, 360)
     assert data.dtype == "uint8"
-    assert data.gmt.registration == 1
-    assert data.gmt.gtype == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.gtype == GridType.GEOGRAPHIC
     npt.assert_allclose(data.y, np.arange(89.5, -90.5, -1))
     npt.assert_allclose(data.x, np.arange(-179.5, 180.5, 1))
     npt.assert_allclose(data.min(), 3, atol=1)
@@ -33,8 +34,8 @@ def test_black_marble_01d_with_region():
     data = load_black_marble(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (3, 10, 20)
     assert data.dtype == "uint8"
-    assert data.gmt.registration == 1
-    assert data.gmt.gtype == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
+    assert data.gmt.gtype == GridType.GEOGRAPHIC
     npt.assert_allclose(data.y, np.arange(4.5, -5.5, -1))
     npt.assert_allclose(data.x, np.arange(-9.5, 10.5, 1))
     npt.assert_allclose(data.min(), 3, atol=1)
diff --git a/pygmt/tests/test_datasets_earth_relief.py b/pygmt/tests/test_datasets_earth_relief.py
index b0851430907..73f543915a5 100644
--- a/pygmt/tests/test_datasets_earth_relief.py
+++ b/pygmt/tests/test_datasets_earth_relief.py
@@ -8,6 +8,7 @@
 from packaging.version import Version
 from pygmt.clib import __gmt_version__
 from pygmt.datasets import load_earth_relief
+from pygmt.enums import GridRegistration
 from pygmt.exceptions import GMTInvalidInput
 
 
@@ -25,7 +26,7 @@ def test_earth_relief_01d_igpp_synbath(data_source):
     assert data.attrs["vertical_datum"] == "EGM96"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -7174.0, atol=0.5)
@@ -45,7 +46,7 @@ def test_earth_relief_01d_gebco(data_source):
     assert data.attrs["vertical_datum"] == "EGM96"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -7169.0, atol=1.0)
@@ -62,7 +63,7 @@ def test_earth_relief_01d_with_region_srtm():
         data_source="igpp",
     )
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -5118.0, atol=0.5)
@@ -79,7 +80,7 @@ def test_earth_relief_01d_with_region_gebco():
         data_source="gebco",
     )
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -5118.0, atol=1.0)
@@ -92,7 +93,7 @@ def test_earth_relief_30m():
     """
     data = load_earth_relief(resolution="30m")
     assert data.shape == (361, 721)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 90.5, 0.5))
     npt.assert_allclose(data.lon, np.arange(-180, 180.5, 0.5))
     npt.assert_allclose(data.min(), -8279.5, atol=0.5)
@@ -110,7 +111,7 @@ def test_earth_gebcosi_15m_with_region():
         data_source="gebcosi",
     )
     assert data.shape == (16, 8)
-    assert data.gmt.registration == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
     npt.assert_allclose(data.lat, np.arange(-87.875, -84, 0.25))
     npt.assert_allclose(data.lon, np.arange(85.125, 87, 0.25))
     npt.assert_allclose(data.min(), -492, atol=1.0)
@@ -183,7 +184,7 @@ def test_earth_relief_15s_default_registration():
     """
     data = load_earth_relief(resolution="15s", region=[-10, -9.5, 4, 5])
     assert data.shape == (240, 120)
-    assert data.gmt.registration == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 4.002083)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.997917)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.997917)
@@ -204,7 +205,7 @@ def test_earth_relief_03s_default_registration():
     """
     data = load_earth_relief(resolution="03s", region=[-10, -9.8, 4.9, 5])
     assert data.shape == (121, 241)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.coords["lat"].data.min(), 4.9)
     npt.assert_allclose(data.coords["lat"].data.max(), 5)
     npt.assert_allclose(data.coords["lon"].data.min(), -10)
diff --git a/pygmt/tests/test_datasets_earth_vertical_gravity_gradient.py b/pygmt/tests/test_datasets_earth_vertical_gravity_gradient.py
index 67070e46541..9851f8ceea9 100644
--- a/pygmt/tests/test_datasets_earth_vertical_gravity_gradient.py
+++ b/pygmt/tests/test_datasets_earth_vertical_gravity_gradient.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_earth_vertical_gravity_gradient
+from pygmt.enums import GridRegistration
 
 
 def test_earth_vertical_gravity_gradient_01d():
@@ -18,7 +19,7 @@ def test_earth_vertical_gravity_gradient_01d():
     assert data.attrs["units"] == "Eotvos"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -40.1875, atol=1 / 32)
@@ -34,7 +35,7 @@ def test_earth_vertical_gravity_gradient_01d_with_region():
         resolution="01d", region=[-10, 10, -5, 5]
     )
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -5.34375, atol=1 / 32)
@@ -50,7 +51,7 @@ def test_earth_vertical_gravity_gradient_01m_default_registration():
         resolution="01m", region=[-10, -9, 3, 5]
     )
     assert data.shape == (120, 60)
-    assert data.gmt.registration == 1
+    assert data.gmt.registration == GridRegistration.PIXEL
     npt.assert_allclose(data.coords["lat"].data.min(), 3.008333333)
     npt.assert_allclose(data.coords["lat"].data.max(), 4.991666666)
     npt.assert_allclose(data.coords["lon"].data.min(), -9.99166666)
diff --git a/pygmt/tests/test_datasets_load_remote_datasets.py b/pygmt/tests/test_datasets_load_remote_datasets.py
index b2de1ebddfa..1f0c49bc4ed 100644
--- a/pygmt/tests/test_datasets_load_remote_datasets.py
+++ b/pygmt/tests/test_datasets_load_remote_datasets.py
@@ -4,6 +4,7 @@
 
 import pytest
 from pygmt.datasets.load_remote_dataset import _load_remote_dataset
+from pygmt.enums import GridRegistration
 from pygmt.exceptions import GMTInvalidInput
 
 
@@ -30,7 +31,7 @@ def test_load_remote_dataset_benchmark_with_region():
     assert data.attrs["long_name"] == "ages (Myr)"
     assert data.attrs["units"] == "Myr"
     assert data.attrs["horizontal_datum"] == "WGS84"
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.shape == (11, 21)
     # Can't access the cpt attribute using virtual files
     # assert data.attrs["cpt"] == "@earth_age.cpt"
diff --git a/pygmt/tests/test_datasets_mars_relief.py b/pygmt/tests/test_datasets_mars_relief.py
index 88c437848f6..e60265b6044 100644
--- a/pygmt/tests/test_datasets_mars_relief.py
+++ b/pygmt/tests/test_datasets_mars_relief.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_mars_relief
+from pygmt.enums import GridRegistration
 
 
 def test_mars_relief_01d():
@@ -17,7 +18,7 @@ def test_mars_relief_01d():
     assert data.attrs["description"] == "NASA Mars (MOLA) relief"
     assert data.attrs["units"] == "meters"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -7421.0, atol=0.5)
@@ -30,7 +31,7 @@ def test_mars_relief_01d_with_region():
     """
     data = load_mars_relief(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -2502.0, atol=0.5)
@@ -44,7 +45,7 @@ def test_mars_relief_01m_default_registration():
     """
     data = load_mars_relief(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_mean_dynamic_topography.py b/pygmt/tests/test_datasets_mean_dynamic_topography.py
index deae6e90a60..c373b727e79 100644
--- a/pygmt/tests/test_datasets_mean_dynamic_topography.py
+++ b/pygmt/tests/test_datasets_mean_dynamic_topography.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_earth_mean_dynamic_topography
+from pygmt.enums import GridRegistration
 
 
 def test_earth_mdt_01d():
@@ -17,7 +18,7 @@ def test_earth_mdt_01d():
     assert data.attrs["units"] == "meters"
     assert data.attrs["horizontal_datum"] == "WGS84"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -1.4668, atol=0.0001)
@@ -30,7 +31,7 @@ def test_earth_mdt_01d_with_region():
     """
     data = load_earth_mean_dynamic_topography(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), 0.346, atol=0.0001)
@@ -44,7 +45,7 @@ def test_earth_mdt_07m_default_registration():
     """
     data = load_earth_mean_dynamic_topography(resolution="07m", region=[-10, -9, 3, 5])
     assert data.shape == (17, 9)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_mercury_relief.py b/pygmt/tests/test_datasets_mercury_relief.py
index 65dbe62e0d1..a81af88066e 100644
--- a/pygmt/tests/test_datasets_mercury_relief.py
+++ b/pygmt/tests/test_datasets_mercury_relief.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_mercury_relief
+from pygmt.enums import GridRegistration
 
 
 def test_mercury_relief_01d():
@@ -17,7 +18,7 @@ def test_mercury_relief_01d():
     assert data.attrs["description"] == "USGS Mercury relief"
     assert data.attrs["units"] == "meters"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -5103.5, atol=0.5)
@@ -30,7 +31,7 @@ def test_mercury_relief_01d_with_region():
     """
     data = load_mercury_relief(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -327.0, atol=0.5)
@@ -44,7 +45,7 @@ def test_mercury_relief_01m_default_registration():
     """
     data = load_mercury_relief(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_moon_relief.py b/pygmt/tests/test_datasets_moon_relief.py
index 87f10ded098..50d20e910ee 100644
--- a/pygmt/tests/test_datasets_moon_relief.py
+++ b/pygmt/tests/test_datasets_moon_relief.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_moon_relief
+from pygmt.enums import GridRegistration
 
 
 def test_moon_relief_01d():
@@ -17,7 +18,7 @@ def test_moon_relief_01d():
     assert data.attrs["description"] == "USGS Moon (LOLA) relief"
     assert data.attrs["units"] == "meters"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -7669.0, atol=0.5)
@@ -30,7 +31,7 @@ def test_moon_relief_01d_with_region():
     """
     data = load_moon_relief(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -1122.0, atol=0.5)
@@ -44,7 +45,7 @@ def test_moon_relief_01m_default_registration():
     """
     data = load_moon_relief(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_pluto_relief.py b/pygmt/tests/test_datasets_pluto_relief.py
index 9979f5915a5..dd6ac599ab4 100644
--- a/pygmt/tests/test_datasets_pluto_relief.py
+++ b/pygmt/tests/test_datasets_pluto_relief.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_pluto_relief
+from pygmt.enums import GridRegistration
 
 
 def test_pluto_relief_01d():
@@ -17,7 +18,7 @@ def test_pluto_relief_01d():
     assert data.attrs["description"] == "USGS Pluto relief"
     assert data.attrs["units"] == "meters"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -3021.0, atol=0.25)
@@ -30,7 +31,7 @@ def test_pluto_relief_01d_with_region():
     """
     data = load_pluto_relief(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -1319.25, atol=0.25)
@@ -44,7 +45,7 @@ def test_pluto_relief_01m_default_registration():
     """
     data = load_pluto_relief(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_datasets_venus_relief.py b/pygmt/tests/test_datasets_venus_relief.py
index f2dc9a9489f..2790ad247e7 100644
--- a/pygmt/tests/test_datasets_venus_relief.py
+++ b/pygmt/tests/test_datasets_venus_relief.py
@@ -5,6 +5,7 @@
 import numpy as np
 import numpy.testing as npt
 from pygmt.datasets import load_venus_relief
+from pygmt.enums import GridRegistration
 
 
 def test_venus_relief_01d():
@@ -17,7 +18,7 @@ def test_venus_relief_01d():
     assert data.attrs["description"] == "NASA Magellan Venus relief"
     assert data.attrs["units"] == "meters"
     assert data.shape == (181, 361)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-90, 91, 1))
     npt.assert_allclose(data.lon, np.arange(-180, 181, 1))
     npt.assert_allclose(data.min(), -2069.0, atol=0.5)
@@ -30,7 +31,7 @@ def test_venus_relief_01d_with_region():
     """
     data = load_venus_relief(resolution="01d", region=[-10, 10, -5, 5])
     assert data.shape == (11, 21)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(data.lat, np.arange(-5, 6, 1))
     npt.assert_allclose(data.lon, np.arange(-10, 11, 1))
     npt.assert_allclose(data.min(), -1244.0, atol=0.5)
@@ -44,7 +45,7 @@ def test_venus_relief_01m_default_registration():
     """
     data = load_venus_relief(resolution="01m", region=[-10, -9, 3, 5])
     assert data.shape == (121, 61)
-    assert data.gmt.registration == 0
+    assert data.gmt.registration == GridRegistration.GRIDLINE
     assert data.coords["lat"].data.min() == 3.0
     assert data.coords["lat"].data.max() == 5.0
     assert data.coords["lon"].data.min() == -10.0
diff --git a/pygmt/tests/test_dimfilter.py b/pygmt/tests/test_dimfilter.py
index 9e998ac9980..3de660e9b4b 100644
--- a/pygmt/tests/test_dimfilter.py
+++ b/pygmt/tests/test_dimfilter.py
@@ -7,6 +7,7 @@
 import pytest
 import xarray as xr
 from pygmt import dimfilter, load_dataarray
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 from pygmt.helpers.testing import load_static_earth_relief
@@ -69,8 +70,8 @@ def test_dimfilter_no_outgrid(grid, expected_grid):
         grid=grid, filter="m600", distance=4, sectors="l6", region=[-55, -51, -24, -19]
     )
     assert result.dims == ("lat", "lon")
-    assert result.gmt.gtype == 1  # Geographic grid
-    assert result.gmt.registration == 1  # Pixel registration
+    assert result.gmt.gtype == GridType.GEOGRAPHIC
+    assert result.gmt.registration == GridRegistration.PIXEL
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
 
diff --git a/pygmt/tests/test_grdclip.py b/pygmt/tests/test_grdclip.py
index a0f2e4a8d7c..d759e28eb91 100644
--- a/pygmt/tests/test_grdclip.py
+++ b/pygmt/tests/test_grdclip.py
@@ -7,6 +7,7 @@
 import pytest
 import xarray as xr
 from pygmt import grdclip, load_dataarray
+from pygmt.enums import GridRegistration, GridType
 from pygmt.helpers import GMTTempFile
 from pygmt.helpers.testing import load_static_earth_relief
 
@@ -51,8 +52,8 @@ def test_grdclip_outgrid(grid, expected_grid):
         assert Path(tmpfile.name).stat().st_size > 0  # check that outgrid exists
         temp_grid = load_dataarray(tmpfile.name)
         assert temp_grid.dims == ("lat", "lon")
-        assert temp_grid.gmt.gtype == 1  # Geographic grid
-        assert temp_grid.gmt.registration == 1  # Pixel registration
+        assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
+        assert temp_grid.gmt.registration == GridRegistration.PIXEL
         xr.testing.assert_allclose(a=temp_grid, b=expected_grid)
 
 
@@ -65,6 +66,6 @@ def test_grdclip_no_outgrid(grid, expected_grid):
         grid=grid, below=[550, -1000], above=[700, 1000], region=[-53, -49, -19, -16]
     )
     assert temp_grid.dims == ("lat", "lon")
-    assert temp_grid.gmt.gtype == 1  # Geographic grid
-    assert temp_grid.gmt.registration == 1  # Pixel registration
+    assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
+    assert temp_grid.gmt.registration == GridRegistration.PIXEL
     xr.testing.assert_allclose(a=temp_grid, b=expected_grid)
diff --git a/pygmt/tests/test_grdfill.py b/pygmt/tests/test_grdfill.py
index f7c4730b744..8d36125c279 100644
--- a/pygmt/tests/test_grdfill.py
+++ b/pygmt/tests/test_grdfill.py
@@ -8,6 +8,7 @@
 import pytest
 import xarray as xr
 from pygmt import grdfill, load_dataarray
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 from pygmt.helpers.testing import load_static_earth_relief
@@ -78,8 +79,8 @@ def test_grdfill_dataarray_out(grid, expected_grid):
     result = grdfill(grid=grid, mode="c20")
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == 1  # Geographic grid
-    assert result.gmt.registration == 1  # Pixel registration
+    assert result.gmt.gtype == GridType.GEOGRAPHIC
+    assert result.gmt.registration == GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
@@ -93,8 +94,8 @@ def test_grdfill_asymmetric_pad(grid, expected_grid):
     result = grdfill(grid=grid, mode="c20", region=[-55, -50, -24, -16])
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == 1  # Geographic grid
-    assert result.gmt.registration == 1  # Pixel registration
+    assert result.gmt.gtype == GridType.GEOGRAPHIC
+    assert result.gmt.registration == GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(
         a=result, b=expected_grid.sel(lon=slice(-55, -50), lat=slice(-24, -16))
diff --git a/pygmt/tests/test_grdfilter.py b/pygmt/tests/test_grdfilter.py
index 5cbe3574767..67c94f6a52c 100644
--- a/pygmt/tests/test_grdfilter.py
+++ b/pygmt/tests/test_grdfilter.py
@@ -8,6 +8,7 @@
 import pytest
 import xarray as xr
 from pygmt import grdfilter, load_dataarray
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 from pygmt.helpers.testing import load_static_earth_relief
@@ -50,8 +51,8 @@ def test_grdfilter_dataarray_in_dataarray_out(grid, expected_grid):
     )
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == 1  # Geographic grid
-    assert result.gmt.registration == 1  # Pixel registration
+    assert result.gmt.gtype == GridType.GEOGRAPHIC
+    assert result.gmt.registration == GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
diff --git a/pygmt/tests/test_grdgradient.py b/pygmt/tests/test_grdgradient.py
index dc082d50d90..c8b6695fa7d 100644
--- a/pygmt/tests/test_grdgradient.py
+++ b/pygmt/tests/test_grdgradient.py
@@ -7,6 +7,7 @@
 import pytest
 import xarray as xr
 from pygmt import grdgradient, load_dataarray
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 from pygmt.helpers.testing import load_static_earth_relief
@@ -66,8 +67,8 @@ def test_grdgradient_no_outgrid(grid, expected_grid):
     )
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == 1  # Geographic grid
-    assert result.gmt.registration == 1  # Pixel registration
+    assert result.gmt.gtype == GridType.GEOGRAPHIC
+    assert result.gmt.registration == GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
diff --git a/pygmt/tests/test_grdhisteq.py b/pygmt/tests/test_grdhisteq.py
index 3c5a3df2d8d..3a9f0740adf 100644
--- a/pygmt/tests/test_grdhisteq.py
+++ b/pygmt/tests/test_grdhisteq.py
@@ -9,6 +9,7 @@
 import pytest
 import xarray as xr
 from pygmt import grdhisteq, load_dataarray
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 from pygmt.helpers.testing import load_static_earth_relief
@@ -78,8 +79,8 @@ def test_equalize_grid_no_outgrid(grid, expected_grid, region):
     temp_grid = grdhisteq.equalize_grid(
         grid=grid, divisions=2, region=region, outgrid=None
     )
-    assert temp_grid.gmt.gtype == 1  # Geographic grid
-    assert temp_grid.gmt.registration == 1  # Pixel registration
+    assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
+    assert temp_grid.gmt.registration == GridRegistration.PIXEL
     xr.testing.assert_allclose(a=temp_grid, b=expected_grid)
 
 
diff --git a/pygmt/tests/test_grdimage.py b/pygmt/tests/test_grdimage.py
index 907886eb0b3..9f11e6a2923 100644
--- a/pygmt/tests/test_grdimage.py
+++ b/pygmt/tests/test_grdimage.py
@@ -9,6 +9,7 @@
 from pygmt import Figure
 from pygmt.clib import __gmt_version__
 from pygmt.datasets import load_earth_relief
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers.testing import check_figures_equal
 
@@ -164,14 +165,15 @@ def test_grdimage_over_dateline(xrgrid):
     """
     Ensure no gaps are plotted over the 180 degree international dateline.
 
-    Specifically checking that `xrgrid.gmt.gtype = 1` sets `GMT_GRID_IS_GEO`,
-    and that `xrgrid.gmt.registration = 0` sets `GMT_GRID_NODE_REG`. Note that
-    there would be a gap over the dateline if a pixel registered grid is used.
+    Specifically checking that ``xrgrid.gmt.gtype = GridType.GEOGRAPHIC`` sets
+    ``GMT_GRID_IS_GEO``, and that ``xrgrid.gmt.registration = GridRegistration.GRIDLINE`
+    sets ``GMT_GRID_NODE_REG``. Note that there would be a gap over the dateline if a
+    pixel-registered grid is used.
     See also https://github.com/GenericMappingTools/pygmt/issues/375.
     """
     fig = Figure()
-    assert xrgrid.gmt.registration == 0  # gridline registration
-    xrgrid.gmt.gtype = 1  # geographic coordinate system
+    assert xrgrid.gmt.registration == GridRegistration.GRIDLINE
+    xrgrid.gmt.gtype = GridType.GEOGRAPHIC
     fig.grdimage(grid=xrgrid, region="g", projection="A0/0/1c")
     return fig
 
@@ -188,8 +190,8 @@ def test_grdimage_global_subset(grid_360):
     """
     # Get a slice of South America and Africa only (lat=-90:31, lon=-180:41)
     sliced_grid = grid_360[0:121, 0:221]
-    assert sliced_grid.gmt.registration == 0  # gridline registration
-    assert sliced_grid.gmt.gtype == 0  # Cartesian coordinate system
+    assert sliced_grid.gmt.registration == GridRegistration.GRIDLINE
+    assert sliced_grid.gmt.gtype == GridType.CARTESIAN
 
     fig = Figure()
     fig.grdimage(
@@ -275,14 +277,16 @@ def test_grdimage_grid_no_redundant_360():
 
     # Global grid [-180, 179, -90, 90] without redundant longitude at 180/-180
     da3 = da1[:, 0:360]
-    da3.gmt.registration, da3.gmt.gtype = 0, 1
+    da3.gmt.registration = GridRegistration.GRIDLINE
+    da3.gmt.gtype = GridType.GEOGRAPHIC
     assert da3.shape == (181, 360)
     assert da3.lon.to_numpy().min() == -180.0
     assert da3.lon.to_numpy().max() == 179.0
 
     # Global grid [0, 359, -90, 90] without redundant longitude at 360/0
     da4 = da2[:, 0:360]
-    da4.gmt.registration, da4.gmt.gtype = 0, 1
+    da4.gmt.registration = GridRegistration.GRIDLINE
+    da4.gmt.gtype = GridType.GEOGRAPHIC
     assert da4.shape == (181, 360)
     assert da4.lon.to_numpy().min() == 0.0
     assert da4.lon.to_numpy().max() == 359.0
diff --git a/pygmt/tests/test_grdlandmask.py b/pygmt/tests/test_grdlandmask.py
index ae51ba2eda4..bfae4cc965c 100644
--- a/pygmt/tests/test_grdlandmask.py
+++ b/pygmt/tests/test_grdlandmask.py
@@ -7,6 +7,7 @@
 import pytest
 import xarray as xr
 from pygmt import grdlandmask, load_dataarray
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 
@@ -53,8 +54,8 @@ def test_grdlandmask_no_outgrid(expected_grid):
     result = grdlandmask(spacing=1, region=[125, 130, 30, 35], cores=2)
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == 1  # Geographic grid
-    assert result.gmt.registration == 0  # Gridline registration
+    assert result.gmt.gtype == GridType.GEOGRAPHIC
+    assert result.gmt.registration == GridRegistration.GRIDLINE
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
diff --git a/pygmt/tests/test_grdproject.py b/pygmt/tests/test_grdproject.py
index 644ac311c54..efd8ae7503d 100644
--- a/pygmt/tests/test_grdproject.py
+++ b/pygmt/tests/test_grdproject.py
@@ -7,6 +7,7 @@
 import pytest
 import xarray as xr
 from pygmt import grdproject, load_dataarray
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 from pygmt.helpers.testing import load_static_earth_relief
@@ -70,12 +71,12 @@ def test_grdproject_no_outgrid(grid, projection, expected_grid):
 
     Also check that providing the projection as an EPSG code or PROJ4 string works.
     """
-    assert grid.gmt.gtype == 1  # Geographic grid
+    assert grid.gmt.gtype == GridType.GEOGRAPHIC
     result = grdproject(
         grid=grid, projection=projection, spacing=3, region=[-53, -51, -20, -17]
     )
-    assert result.gmt.gtype == 0  # Rectangular grid
-    assert result.gmt.registration == 1  # Pixel registration
+    assert result.gmt.gtype == GridType.CARTESIAN
+    assert result.gmt.registration == GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
diff --git a/pygmt/tests/test_grdsample.py b/pygmt/tests/test_grdsample.py
index 4c9e64139c3..7559a791623 100644
--- a/pygmt/tests/test_grdsample.py
+++ b/pygmt/tests/test_grdsample.py
@@ -7,6 +7,7 @@
 import pytest
 import xarray as xr
 from pygmt import grdsample, load_dataarray
+from pygmt.enums import GridRegistration, GridType
 from pygmt.helpers import GMTTempFile
 from pygmt.helpers.testing import load_static_earth_relief
 
@@ -78,8 +79,8 @@ def test_grdsample_dataarray_out(grid, expected_grid, region, spacing):
     result = grdsample(grid=grid, spacing=spacing, region=region, cores=2)
     # check information of the output grid
     assert isinstance(result, xr.DataArray)
-    assert result.gmt.gtype == 1  # Geographic grid
-    assert result.gmt.registration == 1  # Pixel registration
+    assert result.gmt.gtype == GridType.GEOGRAPHIC
+    assert result.gmt.registration == GridRegistration.PIXEL
     # check information of the output grid
     xr.testing.assert_allclose(a=result, b=expected_grid)
 
@@ -88,8 +89,8 @@ def test_grdsample_registration_changes(grid):
     """
     Test grdsample with no set outgrid and applying registration changes.
     """
-    assert grid.gmt.registration == 1  # Pixel registration
+    assert grid.gmt.registration == GridRegistration.PIXEL
     translated_grid = grdsample(grid=grid, translate=True)
-    assert translated_grid.gmt.registration == 0  # Gridline registration
+    assert translated_grid.gmt.registration == GridRegistration.GRIDLINE
     registration_grid = grdsample(grid=translated_grid, registration="p")
-    assert registration_grid.gmt.registration == 1  # Pixel registration
+    assert registration_grid.gmt.registration == GridRegistration.PIXEL
diff --git a/pygmt/tests/test_io.py b/pygmt/tests/test_io.py
index 90ae4f2df83..ade706486e3 100644
--- a/pygmt/tests/test_io.py
+++ b/pygmt/tests/test_io.py
@@ -5,6 +5,7 @@
 import numpy as np
 import pytest
 import xarray as xr
+from pygmt.enums import GridRegistration, GridType
 from pygmt.helpers import GMTTempFile
 from pygmt.io import load_dataarray
 
@@ -22,10 +23,9 @@ def test_io_load_dataarray():
         )
         grid.to_netcdf(tmpfile.name)
         dataarray = load_dataarray(tmpfile.name)
-        assert dataarray.gmt.gtype == 0  # Cartesian grid
-        assert dataarray.gmt.registration == 1  # Pixel registration
-        # this would fail if we used xr.open_dataarray instead of
-        # load_dataarray
+        assert dataarray.gmt.gtype == GridType.CARTESIAN
+        assert dataarray.gmt.registration == GridRegistration.PIXEL
+        # this would fail if we used xr.open_dataarray instead of load_dataarray
         dataarray.to_netcdf(tmpfile.name)
 
 
diff --git a/pygmt/tests/test_nearneighbor.py b/pygmt/tests/test_nearneighbor.py
index 9d08aa0e8d1..aa25c6a0fa3 100644
--- a/pygmt/tests/test_nearneighbor.py
+++ b/pygmt/tests/test_nearneighbor.py
@@ -10,6 +10,7 @@
 import xarray as xr
 from pygmt import nearneighbor
 from pygmt.datasets import load_sample_data
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 
@@ -32,8 +33,8 @@ def test_nearneighbor_input_data(array_func, ship_data):
         data=data, spacing="5m", region=[245, 255, 20, 30], search_radius="10m"
     )
     assert isinstance(output, xr.DataArray)
-    assert output.gmt.registration == 0  # Gridline registration
-    assert output.gmt.gtype == 1  # Geographic type
+    assert output.gmt.registration == GridRegistration.GRIDLINE
+    assert output.gmt.gtype == GridType.GEOGRAPHIC
     assert output.shape == (121, 121)
     npt.assert_allclose(output.mean(), -2378.2385)
 
diff --git a/pygmt/tests/test_sph2grd.py b/pygmt/tests/test_sph2grd.py
index 89b4abeff25..e3c71293621 100644
--- a/pygmt/tests/test_sph2grd.py
+++ b/pygmt/tests/test_sph2grd.py
@@ -7,6 +7,7 @@
 import numpy.testing as npt
 import pytest
 from pygmt import sph2grd
+from pygmt.enums import GridRegistration, GridType
 from pygmt.helpers import GMTTempFile
 
 
@@ -29,8 +30,8 @@ def test_sph2grd_no_outgrid():
     """
     temp_grid = sph2grd(data="@EGM96_to_36.txt", spacing=1, region="g", cores=2)
     assert temp_grid.dims == ("y", "x")
-    assert temp_grid.gmt.gtype == 0  # Cartesian grid
-    assert temp_grid.gmt.registration == 0  # Gridline registration
+    assert temp_grid.gmt.gtype == GridType.CARTESIAN
+    assert temp_grid.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(temp_grid.max(), 0.00021961, rtol=1e-4)
     npt.assert_allclose(temp_grid.min(), -0.0004326, rtol=1e-4)
     npt.assert_allclose(temp_grid.median(), -0.00010894, rtol=1e-4)
diff --git a/pygmt/tests/test_sphdistance.py b/pygmt/tests/test_sphdistance.py
index be8cbd1a066..ac3701fb0c3 100644
--- a/pygmt/tests/test_sphdistance.py
+++ b/pygmt/tests/test_sphdistance.py
@@ -8,6 +8,7 @@
 import numpy.testing as npt
 import pytest
 from pygmt import sphdistance
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 
@@ -29,8 +30,8 @@ def test_sphdistance_xy_inputs():
     x = [85.5, 82.3, 85.8, 86.5]
     temp_grid = sphdistance(x=x, y=y, spacing=[1, 2], region=[82, 87, 22, 24])
     assert temp_grid.dims == ("lat", "lon")
-    assert temp_grid.gmt.gtype == 1  # Geographic grid
-    assert temp_grid.gmt.registration == 0  # Gridline registration
+    assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
+    assert temp_grid.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(temp_grid.max(), 232977.546875)
     npt.assert_allclose(temp_grid.min(), 0)
     npt.assert_allclose(temp_grid.median(), 0)
@@ -56,8 +57,8 @@ def test_sphdistance_no_outgrid(array):
     """
     temp_grid = sphdistance(data=array, spacing=[1, 2], region=[82, 87, 22, 24])
     assert temp_grid.dims == ("lat", "lon")
-    assert temp_grid.gmt.gtype == 1  # Geographic grid
-    assert temp_grid.gmt.registration == 0  # Gridline registration
+    assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
+    assert temp_grid.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(temp_grid.max(), 232977.546875)
     npt.assert_allclose(temp_grid.min(), 0)
     npt.assert_allclose(temp_grid.median(), 0)
diff --git a/pygmt/tests/test_sphinterpolate.py b/pygmt/tests/test_sphinterpolate.py
index d7e24eba780..7b91f00b24e 100644
--- a/pygmt/tests/test_sphinterpolate.py
+++ b/pygmt/tests/test_sphinterpolate.py
@@ -8,6 +8,7 @@
 import pytest
 from pygmt import sphinterpolate
 from pygmt.datasets import load_sample_data
+from pygmt.enums import GridRegistration, GridType
 from pygmt.helpers import GMTTempFile
 
 
@@ -36,8 +37,8 @@ def test_sphinterpolate_no_outgrid(mars):
     """
     temp_grid = sphinterpolate(data=mars, spacing=1, region="g")
     assert temp_grid.dims == ("lat", "lon")
-    assert temp_grid.gmt.gtype == 1  # Geographic grid
-    assert temp_grid.gmt.registration == 0  # Gridline registration
+    assert temp_grid.gmt.gtype == GridType.GEOGRAPHIC
+    assert temp_grid.gmt.registration == GridRegistration.GRIDLINE
     npt.assert_allclose(temp_grid.max(), 14628.144)
     npt.assert_allclose(temp_grid.min(), -6908.1987)
     npt.assert_allclose(temp_grid.median(), 118.96849)
diff --git a/pygmt/tests/test_surface.py b/pygmt/tests/test_surface.py
index e8ec0cf3445..b49e6875304 100644
--- a/pygmt/tests/test_surface.py
+++ b/pygmt/tests/test_surface.py
@@ -8,6 +8,7 @@
 import pytest
 import xarray as xr
 from pygmt import surface, which
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 
@@ -72,8 +73,8 @@ def check_values(grid, expected_grid):
     Check the attributes and values of the DataArray returned by surface.
     """
     assert isinstance(grid, xr.DataArray)
-    assert grid.gmt.registration == 0  # Gridline registration
-    assert grid.gmt.gtype == 0  # Cartesian type
+    assert grid.gmt.registration == GridRegistration.GRIDLINE
+    assert grid.gmt.gtype == GridType.CARTESIAN
     xr.testing.assert_allclose(a=grid, b=expected_grid)
 
 
diff --git a/pygmt/tests/test_triangulate.py b/pygmt/tests/test_triangulate.py
index f0a47c6e4ae..5f9c7a4c319 100644
--- a/pygmt/tests/test_triangulate.py
+++ b/pygmt/tests/test_triangulate.py
@@ -9,6 +9,7 @@
 import pytest
 import xarray as xr
 from pygmt import triangulate, which
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 
@@ -139,8 +140,8 @@ def test_regular_grid_no_outgrid(dataframe, expected_grid):
     data = dataframe.to_numpy()
     output = triangulate.regular_grid(data=data, spacing=1, region=[2, 4, 5, 6])
     assert isinstance(output, xr.DataArray)
-    assert output.gmt.registration == 0  # Gridline registration
-    assert output.gmt.gtype == 0  # Cartesian type
+    assert output.gmt.registration == GridRegistration.GRIDLINE
+    assert output.gmt.gtype == GridType.CARTESIAN
     xr.testing.assert_allclose(a=output, b=expected_grid)
 
 
@@ -157,6 +158,6 @@ def test_regular_grid_with_outgrid_param(dataframe, expected_grid):
         assert Path(tmpfile.name).stat().st_size > 0  # check that outgrid exists
         with xr.open_dataarray(tmpfile.name) as grid:
             assert isinstance(grid, xr.DataArray)
-            assert grid.gmt.registration == 0  # Gridline registration
-            assert grid.gmt.gtype == 0  # Cartesian type
+            assert grid.gmt.registration == GridRegistration.GRIDLINE
+            assert grid.gmt.gtype == GridType.CARTESIAN
             xr.testing.assert_allclose(a=grid, b=expected_grid)
diff --git a/pygmt/tests/test_xyz2grd.py b/pygmt/tests/test_xyz2grd.py
index 56b2d1167e2..9e22d376695 100644
--- a/pygmt/tests/test_xyz2grd.py
+++ b/pygmt/tests/test_xyz2grd.py
@@ -9,6 +9,7 @@
 import xarray as xr
 from pygmt import load_dataarray, xyz2grd
 from pygmt.datasets import load_sample_data
+from pygmt.enums import GridRegistration, GridType
 from pygmt.exceptions import GMTInvalidInput
 from pygmt.helpers import GMTTempFile
 
@@ -48,8 +49,8 @@ def test_xyz2grd_input_array(array_func, ship_data, expected_grid):
     """
     output = xyz2grd(data=array_func(ship_data), spacing=5, region=[245, 255, 20, 30])
     assert isinstance(output, xr.DataArray)
-    assert output.gmt.registration == 0  # Gridline registration
-    assert output.gmt.gtype == 0  # Cartesian type
+    assert output.gmt.registration == GridRegistration.GRIDLINE
+    assert output.gmt.gtype == GridType.CARTESIAN
     xr.testing.assert_allclose(a=output, b=expected_grid)