pg_proc.proacl documentation request

All,

I am looking for documentation on the pg_proc.proacl column. I am working on a schemadiff and when I expect the acl to be the same, they come out slightly different. I searched the PG 7.4 doc site, and didn't find anything except the one liner on the pg_proc description page.

Any kind of documentation, other than the code itself, would be most welcome. :D

Jonathan Scott