filter_from_requires

[Alice Wonder]

While attempting to rebuild a Fedora src.rpm (perl module) in my LFS
system (rpm built from source) - RPM complained that it didn't know what
"filter_from_requires" meant

I think "unknown tag" was the exact complaint.

Thinking it might be Fedora specific macro, I grepped for it in my
F18 /etc/rpm/ directory but nothing.

Any clue what it is I'm missing to tell RPM what to do with that macro?
I am using the /etc/rpm/macros.perl file from Fedora 18 but I think that
particular macro must be defined elsewhere.

Thanks for suggestions.