$property - what are they?

Doing some work in the debugger I have often noticed that in addition to all of the public, protected and private references there are properties prefixed with $. My guess is these are accessors to low-level properties somewhere up in the inheritance chain. But I hate guessing. Anyone know? Are there any advantages to utilizing these properties? Any documentation on them? I can’t find jack on these.

http://opensource.adobe.com/wiki/display/flexsdk/Coding+Conventions

wow… good to know =)