Not a codejock issue per se, but that's where I caught this.

For 19.1 we used codejock 18.6, rather than 18.3, just a case of using the most recent set of sigCJ stuff when we did it, and it never mattered.
For 20 I left it at 18.6, and the first six months or so used that. However last week I made the unpardonable error of letting 20.0 programs compiled with cj18.3 out into the wild. Cue ActiveX errors everywhere, especially as there were still 18.6 programs out there too.

So to my question:

I can see that I could check the local registry to see if a particular version of CJ is on a machine, but in the general case how might I identify if library X version y was used used in a compilation?