text vars in ui xml

[Celestian]

I am still trying to figure this out and wanted to ask a few questions.

How do you know the depth of the parent.* ?

How do you know the variable names? For example if I want to get the name of the target from the eq2ui_mainhud_player.xml how would I know the variable name/depth?

Is there a doc on this I can read and not annoy people with silly questions?