Regex rules based on active URLS

[twiggshub]

I'm trying to understand how the custom search engines work, how to make mine work.

Assume that I have four websites all with the same regex pattern of finding a numerical string of this pattern for example:0-8695000039429 for the active URL and opening it in another search engine (I think the regex /([0-9]-[0-9]{12})/i should work? for this)?

I've looked at the settings-example json in the repo, still can't figure out how to achieve this.

Following the configuration, wouldn't this work to regex out and work as a search engine if I'm on either A B or C, else blank if nothing is regexed from the earlier links?

a|a:ExampleSiteA exampleA.com/#/posts/$s  re=/^(?:a|b|c)\S*?([0-9]-[0-9]{12})/i
blank=exampleA.com/#/posts/$s
b|b:ExampleSiteB exampleB.com/postsview?postid=$s=parse_post=true re=/^(?:a|b|c)\S*?([0-9]-[0-9]{12})/i
c|c:ExampleSiteC exampleC.com//postview?postid=$s /^(?:a|b|c)\S*?([0-9]-[0-9]{12})/i