The enter command attempts to enter a thing or player in the enactor's location.
You can only enter an object if you own it or if it is set ENTER_OK. You must also pass the enter-lock, if it is set.
Entering an object triggers its @enter/@oenter/@oxenter
messages and its @aenter actions. If you fail the enter-lock, the
object's @efail/@oefail/@aefail messages and actions are triggered.
The @ealias command can establish aliases that can be used to enter the object instead of using the enter command (e.g. 'board ship').
You can describe the interior of an object differently from its exterior by using @idescribe.
Once inside an object, the leave command can be used to leave.