Apparent inconsistent use of upper case in room names

The Spare Room is a room. Etc… compiles as “Spare Room”.
The Corridor is a room. Etc… compiles as “corridor”.

Is it because corridor is a one-word room?

The first time you refer to the corridor in the code it’s written in lower case, which defines the room implicitly. Search for “corridor” in the source text and check the first time it’s mentioned.

Thank you very much. I would never have thought of that!