What alternative syntaxes are there for expressing XML?

What human-readable and human-editable syntaxes exist that can be automatically converted to and from XML with no loss of expressivity. In other words, an updated version of this list. The three syntaxes mentioned there are:

• SOX
• PYX
• SLiP

Are there others? (This isn't about alternatives to XML, like JSON, but simply easier ways for humans to maintain XML files using a text editor).

Some more answers:

• CompactXML - one alternative general purpose XML syntax, looks fairly sensible
• SLAX - an alternative syntax for XSL. Looks like an odd hybrid of JavaScript, CSS, and...I'm not sure.
• RELAX NG - a schema language for XML (like XSL), with a compact alternative syntax.

And some useful links:

• XSugar - interesting paper about the problem
• XFlat - a general tool for converting between definable "flat" formats and XML. (So not a particular syntax)
• XSCS - a paper describing something very similar to CompactXML above. I think.