%%GDBM%% is there because GDBM support is an option, and @@gdbm@@ because the file gets in a subpackage.

It is still a review because stuff still need to be discussed ;-)

For example, if OPT_SUBPACKAGES is defined, does it mean that files guarded by %%OPT%% automatically get in the subpackage set in there? What if opt_SUBPACKAGES defines more than one subpackage? What if some files from option opt should go in a different subpackage, say the "doc" one?

Just some thoughts, feel free to ignore:

• when defining OPT_SUBPACKAGE (e.g. OPT_gdbm) it would be a nice idea to automatically move the %%GDBM%% files into the gdbm subpackage, so e.g. %%gdbm%%%%ARCH_LIB%%/GDBM_File.pm (so using lowercase option names to combine the subpackage and the regular option names). This way we can reduce some red tape.
• When GDBM_File.pm should go into multiple/different subpackages: %%GDBM%%@@doc@@%%ARCH_LIB%%/GDBM_File1.pm %%GDBM%%@@gdbm@@%%ARCH_LIB%%/GDBM_File_Explicit.pm %%gdbm%%%%ARCH_LIB%%/GDBM_File_Implicit.pm

This combining option and subpackage names is not foolproof, there are a few ports with lowercase option names (one qt4/kde4-using port IIRC).

I feel the semantics would get overly complicated and confuse people.

Options MUST be uppercase, I think there is a QA check for this. I do not remember finding ports with lowercase options, but in any case, they should be fixed.

Yes, probably better to leave the option and subpackage name split.

It was the QA check that notified me of that port ;)