Here's the definition, covering the Call Report (Secured by multi-family - 5 or more)
Report in column B all other nonfarm residential loans secured by real estate as evidenced by mortgages (FHA and conventional) or other liens that are not reportable in Schedule RC-C, part I, item 1.c.Specifically, include loans on:
(1)Nonfarm properties with 5 or more dwelling units in structures (including apartment buildings and apartment hotels) used primarily to accommodate households on a more or less permanent basis.
(2)5 or more unit housekeeping dwellings with commercial units combined where use is primarily residential.
(3)Cooperative-type apartment buildings containing 5 or more dwelling units.
Exclude loans for multifamily residential property construction and land development purposes (report in Schedule RC-C, part I, item 1.a).Also exclude loans secured by nonfarm nonresidential properties (report in Schedule RC-C, part I, item 1.e).