A label definition consists of an identifier followed by a colon (:). Label definitions assign the current value and type of the location counter to the name. An error results when the name is already defined.
Label definitions always end with a colon. You can put a label definition on a line by itself.
A generated label is a single numeric value (1-255). To reference a generated label, put an f (forward) or a b (backward) immediately after the digit. The reference tells the assembler to look for the nearest generated label that corresponds to the specified number in the lexically forward or backward direction.