What are labels used for (in attributes description)?

[Roni Yaniv]

I haven't seen that field mentioned anywhere.

[Jim Reardon]

They are just one way you can organize things; ideally search would be implemented (code.google.com's issue tracker has an excellent implementation that would have been excellent to base it upon).  Appengine full-text search is in testing (I think; it's possible it's been released), and would be ideal for it.

- Jim