Thanks for the explanation.  I now see that some the the same material
is in mk/buildlink3/BUILDLINK3_DG:

     Q2: Why can't I check the values of variables set by the buildlink3
	 framework using 'make show-var VARNAME=...'?

     A2: Some variables are only defined for a subset of the package build
	 phases.  Try instead:

	     make show-var PKG_PHASE=wrapper VARNAME=...

 > The buildlink stuff is only used in some phases of the package; for
 > example, it's useless during the fetch, so it can be omitted at parse
 > time to speed up make runs.  Therefore, in order to get the
 > appropriate values for those variables, you need to specify the phase
 > in which they are meaningful.  For example:
 > 
 >     make show-var VARNAME=BUILDLINK_PREFIX.qt3-libs PKG_PHASE=configure

Anyway, the following commands still return nothing (as does any other
phase used instead of wrapper):

	cd devel/bison
	make show-var PKG_PHASE=wrapper VARNAME=PKG_PREFIX.gettext-lib

Note:  here is the bit from the bison Makefile that I expected would
cause PKG_PREFIX.gettext-lib to be defined.

	.include "../../devel/gettext-lib/buildlink3.mk"

I must still be missing something.  Could someone please verify that
they see the same thing.  When is PKG_PREFIX.* visible as a value?
Any further help is greatly appreciated.

Thanks alot.

Cheers,
Brook