Can you please tell me what capping a zone means?

I recieved a survey for elk hunting in Idaho and one of the questions asked me if
I hunt in a capped zone, and if it affected where I hunt. I'm not sure what that means.

Answer: 

To manage game in some of the elk zones we have established, we only allow a limited number of tags to be sold.
The capped zones are:
Dworshak zone B tags
Lolo A & B tags
Elk City zone B tags
Selway zone A & B tags
Middlefork zone A & B tags
Salmon zone B tags
Sawtooth zone A & B tags
Smoky Mountain zone A & B tags
Diamond Creek zone A tags
Resident capped zone tags go on sale on July 10 (midnight mountain time)
Nonresident capped zone tag go on sale Dec 1 of the year before.
 

Answered on: 
Thursday, June 14, 2012 - 9:34 AM MDT