A.5. LABEL Phrase

The LABEL phrase may be used to specify a name for the DO or LOOP. The can optionally be used for

a LEAVE instruction to identify the block to be left
an ITERATE instruction to identify the loop to be iterated
the END clause of the block, for additional checking.

Example A.9. Simple LOOP block with label

Loop label outer I=1 to 10 by 2
   ...
   if i > 5 then do label inner
      ...
      if a = b then leave inner
      ...
      if c = b then iterate outer
   end inner
   ...
   say i
end outer
/* Displays: "1" "3" "5" "7" */

In this example, the LEAVE instruction will exit the inner DO block. The ITERATE instruction will iterate the out LOOP instruction.

If a LABEL phrase is used on a DO or LOOP, it overrides any name derived from any control variable name. That is, if label is used, the control variable cannot be used on a LEAVE, ITERATE, or END instruction to identify the block. Only the label name is valid.