Google

NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.7">

Booleans

Booleans are created just like longs, but have the type IS_BOOL. Allowed values in lval are 0 and 1:
zval *new_bool;

MAKE_STD_ZVAL(new_bool);

new_bool->type = IS_BOOL;
new_bool->value.lval = 1;
The corresponding macros for this type are ZVAL_BOOL (allowing specification of the value) as well as ZVAL_TRUE and ZVAL_FALSE (which explicitly set the value to TRUE and FALSE, respectively).