The plug-in vendor should explain this in the accompanying documentation.
In the plug-ins I use (I don't use Regex) it's done with the Version() function. If not present the result is "?". Which you can test.
If [Left ( SDialog_Version ( "long" ) ; 24 ) ≠ "24U SimpleDialog Plug-In"]
Show Custom Dialog ["Error"; "The 24USimpleDialog Plug-in could not be found.¶¶Install this plug-in and try again"]
Close File [Current File]
Thank you for your quick reply. That does the trick.
Well you get what you pay for and regex is free and the documentation a bit sparse!
But it does what I need in a relatively simple manner.
I got hung up on error codes and didn't think about being able to check getVersion not matching.