The role of Role in Schema.org

The role of Role in Schema.org<http://Schema.org>

An explanation of this very useful feature that turned into a blog post.
http://dataliberate.com/2015/04/the-role-of-role-in-schema-org/

An obvious candidate for the documentation being discussed here recently.  More than happy to copy it in once we have decided what we are doing.

~Richard