I often find that I have misunderstood somebody else's poem, and I notice also that my own get misunderstood by others reasonably often. How about a box available to people posting poems, where the poet can say something about his or her poem, such as what inspired it, what is the real theme, even explaining some references in it to particular places or people or events that might not be familiar to readers from other countries? Completion of the box should be optional. Perhaps a word limit of, say, 200 words?

Why not leave a comment on your own poem after it is published?

Or include it with the poem, set off by asterisks. I like the suggestion and understand the reasoning, but think it can be accomplished without adding a special field for it.

Well, those are both options, and I've done the second sometimes (without asterisks!), but a special field would encourage people to say something about their poems at time of posting, and that is something that is very rare. I think it would be a good idea to encourage it explicitly.