4.2.1 Label

A label is one or more characters chosen from the set composed of all letters, digits, the underline character (_), and the period (.). Labels may not begin with a decimal digit, except for the special case of a local symbol. (See Local Symbols for more information.) Case is significant. There is no length limit; all characters are significant.

Label definitions must be immediately followed by a colon. A space, a tab, an end of line, or assembler mnemonic or directive may follow the colon.

Label definitions may appear on a line by themselves and will reference the next address.

The value of a label after linking is the absolute address of a location in memory.