Definition: Letter = (A-Z, a-z or '$' or '_' ) Definition: Digit = ( 0 -9 )
An Identifier: Must begin with a letter, '$', or "_". After the first char, any char that is a letter (including '$' or '_') or digit may be used. Cannot be a reserved word (aka keyword). No spaces are allowed in the identifier. Cannot have a Java operator symbol (because not a letter or digit). No limit to the number of letters & digits (0 - 9).