The placing of things into named classes. Classification imposes an order; it does not find one lying there.

Written explanation kept beside a thing so others can use it. Documentation is a claim, and it drifts from the truth unless tended.

One surface of a larger work. A unit of reading, bounded by how much a reader can hold at once.

Parallel surfaces sharing one frame, of which one shows at a time. What is hidden is not gone, only behind.