Here you go Sue the link is at the bottom of the page. I carry this with me if the only room with a rollin shower has a king bed I ask for the manager and show them the law. Sometimes they know the law but the desk people don't and sometimes the managers don't know the law but I show it to them and tell them they are more then welcome to call their corporate office and ask for the compliance staff.
9. Violations with respect to guest rooms generally
a. A second set of room number signs will be installed.
The new room number signs will be mounted on the wall
adjacent to the latch side of the door at a height
above the floor of 60 inches to the centerline.
b. i) In order to provide individuals with disabilities
a range of option equivalent to those available to
other individuals served by the hotel, including
the opportunity to stay in a sleeping room with
two beds, Johnson Creek Hospitality shall provide
to any guest with a disability who requests an
accessible room with two beds, one of its
accessible rooms (each of which has only one bed),
and an adjoining room (with one or two beds), for
the price of one room with two beds. Johnson
Creek Hospitality shall insure that all of its
front desk personnel are aware of this requirement
and comply with it. Complying with this
requirement will require Johnson Creek Hospitality
to reserve, until all other rooms are rented, not
only its accessible rooms, but also at least one
standard room adjoining an accessible room, so
that the option of an accessible room with two
beds will remain available to individuals with
disabilities.
http://www.usdoj.gov/crt/foia/diwi1.txt
You can find the above part in exhibit 2 section 9.