Seperate 'requires' lists for .src RPMs?

[Max TenEyck Woodbury <mtew cds duke edu>]

Since building an RPM from its sources may require some packages that 
simply running the package does not, is there a way to specify the extra
requirements? 

In particular, source packages may require 'development' versions of some 
libraries to be installed so that the 'headers' that are used by the build 
process are available.

mtew