NOP is a dummy instruction that has no effect. It can be useful as the target of a THEN or ELSE clause.
Example 2.30. Instructions - NOP
Select
when a=c then nop /* Do nothing */
when a>c then say "A > C"
otherwise say "A < C"
end
Note
Putting an extra semicolon instead of the NOP would merely insert a null clause, which would be ignored. The second WHEN clause would be seen as the first instruction expected after the THEN, and would, therefore, be treated as a syntax error. NOP is a true instruction, however, and is, therefore, a valid target for the THEN clause.
