How search.cpan.org displays the contents of modules is pretty much a black box

Yes - though in this instance it seems that 'no_index' does the trick. Both PAR and Win32::SharedFileOpen appear to be using it to hide the '.pm' files that are located in the 'inc' folder.

I had only just uploaded a new version of my module before I started to wonder about it. The next version (which could be a while away) will include a META.yml - and then I'll find out for sure :-)

Cheers,
Rob