What is the shortest poem?

[RiverNotch]

Yoko Ono's Yes was pretty good. It's called a painting but it doesn't really matter what it's called..

Back in November 1966, she exhibited her "Ceiling Painting" (or the "YES Painting") at the Indica Gallery of London. Viewers had to climb up a white ladder in the center of the room, from where a magnifying glass hanging from the ceiling allowed them to view the word "YES" written in tiny letters on a framed piece of paper affixed to the ceiling.

Does it, though? Doesn't calling a something a piece of poetry make the criteria for judging it a bit different than calling it, say, a painting, or a piece of music?

And if it seems like a rhetorical question, which it kinda does to me, well it isn't, and I don't really know much about other fields in terms of their, er, proper definitions and whatnot for me to give a good answer. Anyone?