Log Message:
-----------
Clarify NULLIF example
found by "Vesa-Matti J Kari" <vmkari(at)cc(dot)helsinki(dot)fi>
Modified Files:
--------------
pgsql/doc/src/sgml:
func.sgml (r1.482 -> r1.483)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml?r1=1.482&r2=1.483)