manage external namespace in Protege

I’d like to know how to refer to an object property in external namespace in Protege.
say I want to set the 'event:time' property to a 'http://purl.org/NET/c4dm/event.owl#event' object,
the range of a event:time is time:TemporalEntity(http://ww.w3.org/2006/time#),
do I have to explicitly declare the time:TemporalEntity class in my class heriachy?
And I couldn’t find the event:time in the property hierarchy, do I need to redefine or declare it?

Best regards.

Received on Tuesday, 24 March 2015 17:57:08 UTC