stupid question - what's the string box under "invert&q

[Ron]

This box is a free-comment box. You can put in here whatever you like. I still have to add a label to it :-) so people recognise it.

[mcguyton]

When learning commands you can enter a string (in the box under the "invert" checkbox).

What's this string for?
How is its use different than the one that names the EventString (in the command tree on the left)?