You use labels to give symbolic names to addresses of instructions or data. The most common form of label is a code label where code labels as operands of call, branch, and jump instructions to transfer program control to a new instruction. Another common form of label is a data label which labels a data storage area.
Syntax
label [:] [directive | instruction]
The label field starts at the left of the line, with no preceding spaces. The colon after the label is optional, but if present the assembler immediately defines the label as a code or data label. Some directives, such as EQU, require that you do not place a colon after the label.
Example
ExitPt: RET
This defines ExitPt as a code label which labels the RET instruction. You can branch to the RET instruction by using the label ExitPt in an instruction:
BRA ExitPt