The source in the .zip, .tgz and .src.rpm is the same.  The archive files
contain all platform source (windows, unix, vms)

If you have a 0.xx version you should upgrade to a 1.xx version as the
format changed, and the version 0 format is being phased out.

The .spec file is also contained in the .src.rpm file.  On some systems you
can build direct from the spec file, which downloads the source from this
directory.

The .asc files are signatures of the other files.  The .asc files are signed
with the key rpm-key.asc.  (Which is turn signed by the adam-key.asc key.)

The .src.rpm is signed with the rpm-key.asc.  (Which is in turn signed
by the adam-key.asc key.)