ICF MR/DD is a designation referring to an ICF (intermediate care facility) for either MR (mental retardation) or DD (developmental disability) or both (MR/DD). The distinction between MR and DD is not clear in this context; some facilities designated only "MR" (ICF MR) will accept DD patients, and possibly vice-versa. It may be that there are no specific criteria. (Further research is needed.)
More descriptively, an ICF MR/DD is a long-term residential facility with 24-hour supervision and nursing care (see ICF) designed for patients with some form of developmental disability.
This terminology appears to be in use in at least the following states: Kentucky, North Carolina, Ohio (possibly also South Dakota and Wisconsin)
"MR" is arguably a type of "DD", making ICF-MR a subclass of ICF-DD or ICF-MR/DD; see HTYP:Usage/MR-DD for disambiguation and usage of these terms within HTYP.