Here is the regulation in the 97 UPC
804.0 Indirect Waste Receptors
804.1 All plumbing fixtures or other receptors
receiving the discharge of indirect waste pipes shall
be approved for the use proposed and shall be of
such shape and capacity as to prevent splashing or
flooding and shall be located where they are readily
accessible for inspection and cleaning. No standpipe
receptor for any clotheswasher shall extend more
than thirty (30) inches (762 mm), nor less than
eighteen (18) inches (457 mm) above its trap. No trap
for any clotheswasher standpipe receptor shall be
installed below the floor, but shall be roughed in not
less than six (6) inches (152 mm) and not more than
eighteen (18) inches (457 mm) above the floor. No
indirect waste receptor shall be installed in any toilet
room, closet, cupboard, or storeroom, nor in any
other portion of a building not in general use by the
occupants thereof; except standpipes for
clotheswashers may be installed in toilet and
bathroom areas when the clotheswasher is installed
in the same room.