The following apply when you create a variable name or constant.
They must begin with a letter.
They can contain the letters A to Z and a to z, the underscore "_", and the digits 0 to 9.
They cannot be longer than 40 characters.
They cannot match the reserved words nor any of the available constants. (One exception to this rule is that object member names and property names may be reserved words.)
For a table of reserved words, see "Functions, Statements, Reserved words - Quick Reference".
For information on the available constants, see "Enumerated Constants Overview".