XML is a bad idea.
If you ever think "Oh I could use XML for this" then just take a step back, insert a large metal spike into your ear, extract it via the other ear, and then think again.
Just say "no" to XML. It's your civic duty.
"actually, the industry uses a plethora of standards, of which XML is only one. However as a whole, the world is moving away from XML due to various unpleasantnesses. Don't you want to be building future-proof systems?"