repomd.xml product matching

Hi, this is the thread to discuss the repository metadata to specify 
which products this repository was created for, and for what purpose.

On the call, it was suggested to use:

<distro>
  <id></id>
  ...
</distro>

Where the id is specified as a 
http://cpe.mitre.org/files/cpe-specification_2.0.pdf string.
 
I would rename distro to platform (because we are using cpe) and it is 
more generic for addons products.

For specifying purpose, we said using generic tags would be ok:

<keywords>
  <k>update</k>
  <k>unstable</k>
</keywords>


And clients could interpret those tags.

Comments?
Duncan