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