wording of messages [was: Re: Movement on @summary]

Henri Sivonen asked:

> I don't like the idea of HTML 5 prescribing UI strings for any class
> of product, but what would you write (max 2 sentences) as the message
> (let's avoid the word "warning" for now) emitted by a validator upon
> seeing an attribute called summary on an element called table?

Would something like the following be acceptable?

The summary attribute is normally invisible; would this particular
summary be better as part of the caption or legend?

-jJ