What is the format for GeoShape properties?

I'm currently helping Drupal's Geofield team figure out how to place
microdata for their field.

Is there a standard or examples that I can refer to for figuring out how to
format the GeoShape properties? The descriptions aren't really precise
enough.

   - box
   - circle
   - elevation
   - line
   - polygon

Thanks,
Lin


-- 
Lin Clark
Drupal Consultant

lin-clark.com
twitter.com/linclark