First, this Axiom is super-small. Compiled, it's about 60 bytes.
Anyways, it is an optimized form of GetKey when you only want ONE of the four arrow-keys.
For example, if I'm making a maze game where the player can only move up, down, left, or right, but not 2 at once, this would be perfect.
The command is the Zoom In token, with no modifiers.
Also, the version for your calc is a program. If you have it in RAM when you compile something using it, Axe will convert it to an Appvar, and put it into archive. You can then delete the program.