This description is provided by Olive Thexton of Fylde Branch

MI's - Monumental Inscriptions

Inscriptions written on gravestones that have been copied and transcribed to paper or microfiche. These can be borrowed from LFHHS branches, seen at Libraries or purchased from the Society. 

Mi's can give extra information, such as relationships, dates and names of other people interred in the grave or just mentioned on the gravestone, and are extremely useful to family historians.