Requirements for a -devel package: are these written down?

[Jonathan Robie]

I got a BZ for a package I maintain from someone who needs multilib 
support without using Mock:

https://bugzilla.redhat.com/show_bug.cgi?id=595923

I found myself asking what the requirements are for a -devel package. In 
general, do we support this in -devel libs or not? On IRC, I think I've 
learned that the answer is "yes", but ....

.... this also made me realize that I really don't know what other 
requirements we may have for -devel packages, I wondered if everyone 
building -devel packages is providing multilib support, and I wondered 
if we need some way to detect conflicts among headers for multiple 
architectures.  In this case, the problem was a conflict in the size of 
a long:

#define XERCES_SIZEOF_LONG 4
vs.
#define XERCES_SIZEOF_LONG 8

Are there other requirements for -devel packages that I should be aware 
of? Is there something I should read?

Jonathan