IF Statement:

  
<if statement>       	::= <if clause> <statement> 
			  | <if clause> <true part> <statement> 
			  | <label definition> <if statement>

<if clause>		::= IF <expression> THEN 

<true part>	        ::= <basic statement> ELSE
 
The <expression> in the <if clause> is evaluated and, if necessary converted to a conditional. If the value is true the <true part> is executed and control passes to the next statement. If it is false either the statement following the else is executed if the else is present, or else the next statement is executed.

Conversion of a fixed value to a conditional is made based on the least-significant bit, 1=true and 0=false.