Section - Extended Grammar for Enter

Understand the command "board" as "enter".
Understand "climb on/onto/in/into [something enterable]" as entering.
Understand "exit [a door]" or "exit through/using/by/out [a door]" as entering.
Understand "sit [something]" as entering. [Note: This breaks I7 [recap of command] / I6 PrintCommand, which expects the player has typed a grammatical command. Thus we might get messages like "What do you want to sit?"]
Understand "sit down on/in [something]" as entering.
Understand "jump on/in/into/onto [something]" as entering.
Understand "sit down" as entering.