Returns 
if condition 
is non-zero (true); otherwise returns 
.
if condition is non-zero (true); otherwise returns . @recode |
if condition is non-zero (true); otherwise returns . 
if 
is non-zero (true); otherwise returns 
. 
is specified using an expression with a boolean operator or function returning (0, 1) values (e.g., “z > 3”or “z > w”), but any argument providing (0, non-zero) values is sufficient.