In a multiple-family residential district, no building or land shall be used and no building shall be erected except for one or more of the following specified uses unless otherwise provided in this ordinance:

1.

All uses in the R-2, two-family residential district, permitted and as regulated under section 501.

2.

Multiple-family dwellings.

3.

Boarding houses.

4.

Accessory buildings and uses customarily incident to any of the above permitted uses.