Looking at the program you might assume the ELSE belongs to the first IF. However,the languageprocessor associates an ELSE with the nearest unpaired IF. The outcome is as follows:
What a lovely day!
We should take our raincoats!
/******************************** REXX *******************************/
/* This program demonstrates what can happen when you do not include */
/* DOs, ENDs, and ELSEs in nested IF...THEN...ELSE instructions. */
/*********************************************************************/
weather = 'fine'
tenniscourt = 'occupied'
IF weather = 'fine' THEN
SAY 'What a lovely day!'
IF tenniscourt = 'free' THEN
SAY 'Let''s play tennis!'
ELSE
SAY 'We should take our raincoats!'
Figure 17. Example of Missing Instructions
Control Flow within a Program
Chapter 4. Controlling the Flow within a program 35