I called the first one “pre” since it “precedes” the others.

I called the last one “pro” since it “proceeds” from the others.

These are somewhat poetic/whimsical terms, for an abstract arrangement, but it’s nice to have good terms even for non-serious stuff.

I couldn’t come up with an equally concise term for the middle.

Claude came up with “per” as in “through” for the middle thing.

Couldn’t be more fitting.