Selection among alternatives: The if instruction.

if condition [then]
  {instruction}
{elsif condition [then]
  {instruction}}
[else
  {instruction}]
(end | endi)

The conditions are evaluated in the sequence presented, until one evaluates to True. The corresponding sequence of instructions is then carried out, followed by the instruction coming after end. If an else clause is present, and all the conditions are false, the instructions following the else are carried out. If there is no else clause and all the conditions are false, the instruction has no effect.

Herman Venter

This is Slim documentation as snarfed on 27 May 1999 by dB.