procedure If([!]param1,op,[!]param2,...)

Conditional statement.  A "!" represents a boolean operator NOT.  Boolean operaters & (and) | (or) can be used.

Example:

if (good,&,!abort) 
... statements if TRUE
elseif
... statements if FALSE
endif;

or

if(!good)
...statements if TRUE
endif;

Also see:  EvalBoolean