Label for a BEGIN-END compound statement in the procedure, or for an iteration statement (WHILE, LOOP, FOR and REPEAT).
The beginning label must be suffixed with a COLON character (:). An ending label is not mandatory, but if an ending label is specified, you must also specify an equivalent beginning label.
The label name of the BEGIN-END compound statement cannot be reused in an iteration statement. A label name cannot be reused within a group of nested compound statements or nested iteration statements, but can be reused for different non-nested iteration statements or non-nested compound statements.
Using label names for each BEGIN-END compound statement is recommended if you specify nested compound statements in an SQL procedure.
A local variable can be optionally qualified with the label of the corresponding compound statement in which the variable is declared. This helps in avoiding conflicts that might be caused by duplicate local variables in nested compound statements.