Chapter 5. Language elements
5.1. Identifiers
Identifiers are used to name variables and functions. They are an alphanumeric sequence that may include the underscore (_) and dollar sign ($) characters. They have the same syntax as C identifiers, except that the dollar sign is also a legal character. Identifiers that begin with a dollar sign are interpreted as references to variables in the target software, rather than to SystemTap script variables. Identifiers may not start with a plain digit.