MIIS is a MUMPS-like programming language developed by Meditech in the 1970s. When many MUMPS implementations standardized to be compatible, MIIS did not standardize, but became a proprietary system instead.

As an example of the differences between MUMPS and MIIS, the value of a logical expression in MUMPS may be false = zero (0) or true = one (1). In MIIS, the value false is the ASCII character "nul" (byte with all 0 bits = binary 0) and the value of true is "del" (7 bits of a byte with all 1 bits = binary 127). (note: ASCII is not a 8-bit standard, but a 7-bit standard).