Level locked - Term that applies to areas in the game that you cannot
enter after you gain a certain level.  For example, an area that is 
level locked at 15 means that you cannot access the area any time
after level 15.  It works the same for 18, 20, 25, 35, 45, etc.

Areas that are reverse level locked are blocked to you until you
attain a certain level.  For example, an area reverse level locked
at 35 would be inaccessable until you were level 35.

The level lock can be viewed with the 'levellock' command.