The Art of Assembly Language, 2nd Edition

7.2 Statement Labels

Assembly language low-level control structures make extensive use of labels within your source code. A low-level control structure usually transfers control between two points in your program. You typically specify the destination of such a transfer using a statement label. A statement label consists of a valid (unique) HLA identifier and a colon. For example:

aLabel:

Of course, as for procedure, variable, and constant identifiers, you should attempt to choose descriptive and meaningful names for your labels. The example identifier above, aLabel, is hardly descriptive or meaningful.

Statement labels have one important attribute that differentiates them from most other identifiers in HLA: You don't have to declare a label before ...