properties with $ prefix in Flex

Question

What is the significance of the $ prefix on some properties of Flex Objects?

e.g. item.$width

Answer 1

The $identifier notation is the used naming convention for mx_internal functions (mostly getters/setters) in the Flex SDK. Whereas the _identifier convention is used for private and mx_internal variables.

For the exact definition of the naming conventions check this page: Coding Conventions - Flex SDK