Vague question about <visible>

Hi,

This question is coming from the perspective of a non-programmer and it’s about the visible tag.
I have always sort of assumed that XML was just an advanced way of storing variables, but to me the visible tag looks different. Take the following:

<visible>!String.IsEqual(Playlist.Length(music),0)</visible>

To a non-programmer such as myself this looks like code; IF a string length is not zero, THEN do something. The visible tag is filled with what I think are called conditionals. Maybe they’re Booleans; and, or, not or, not and, equal, not equal.

Regardless of their proper name, my vague question is whether it’s just me over-reaching or is this kind of a big deal? This seems pretty cool.