application icon locations and cache update

[Eric Smith]

I just learned in a package review about the requirement to update the 
icon cache:

     http://fedoraproject.org/wiki/Packaging:ScriptletSnippets#Icon_Cache

I'm checking my other packages that have icons.  I discovered that one 
of my packages installs its icon into /usr/share/pixmap, rather than 
under /usr/share/icons/<something>.  This raises two questions:

1)  Is putting the icon into /usr/share/pixmap OK?  I think I copied 
this from another package, and certainly there are other applications 
that have their icons there.  If putting the icon into /usr/share/pixmap 
isn't the best practice, how do I know which subdir of /usr/share/icons 
to use?  Is there a document that defines the purpose or requirements 
for the various subdirs?

2)  If it is OK to put the icon into /usr/share/pixmap, do I still need 
to update the icon cache?  As I recall, I did have a great deal of 
hassle with the icon when I was creating this package, probably due to 
not updating the cache.  The instructions on the page linked above only 
describe this for subdirs of /usr/share/icons, though perhaps the same 
script would be applicable.

Thanks!
Eric