Reworded definition text and expanded types that callSign is used on.
Reworded definition text and expanded types that callSign is used on.

This addresses issue #2372.

schemaorg/schemaorg,vholland/schemaorg,schemaorg/schemaorg,schemaorg/schemaorg,vholland/schemaorg,vholland/schemaorg,schemaorg/schemaorg,schemaorg/schemaorg,vholland/schemaorg