Adding annotated text to UI layouts

Is there any mel commands for adding annotations in UI layouts? I would like to create attributes then have a text line under them explaining their usage.

Attr1 = (on/off)
. . .this attr controls. . .

I think just about any kind of control (not layout) can have an annotation added to it like:
button -l "Bla!" -c "crashComputer" -ann "Don't press";
There is an "-ann" flag for layouts as well, but I've never tried it.