You can use uppercase letters, lowercase letters, numeric characters, or the underscore character in symbol names.

Do not use numeric characters for the first character of symbol names, except in local labels (see Local labels).

Symbol names are case-sensitive.

All characters in the symbol name are significant.

Symbol names must be unique within their scope.

Symbols must not use built-in variable names or predefined symbol names (see Predefined register and coprocessor names and Built-in variables).

Symbols must not use the same name as instruction mnemonics or directives. If you use the same name as an instruction mnemonic or directive, use double bars to delimit the symbol name. For example:

The bars are not part of the symbol.