The caretaker's cupboard

The keys were labelled, with a room number fixed to every ring. They were secured inside a locked cabinet rather than left on hooks beside the desk. The caretaker explained the signing-out sheet before handing me the one I needed. I had been irritated by the delay because the meeting room was only upstairs. Seeing the full board made the delay seem more reasonable: each small piece of metal opened something that somebody else relied on.

From the passage, select two words or phrases that describe how the keys were organised and protected.