Acronym for the "Ted Mao Scale of Siblic Identicality", "a logarithmic scale from 0 to 10 that describes the similarity between siblings." Such a rating is called an MSIR (MSI rating). It can be broken down into sub-scales of MSIRP (physical similarity) and MSIRB (behavioral similarity).
Excerpt of description of the siblings Ted, Eric, Brian Mao:
MSIRP = 9.990, MSIRB = 9.93, MSIR = 9.96
Identical triplets where two of the three embryos were extracted from the mother's womb, frozen, then each released a few years apart. Physical appearances are identical except for slight age differences. There are greater acquired behavioral differences than normal triplets because they grew up a few years apart. Only other differences: eyesight (Eric: +200/+200; Brian: +550/+500; Ted: +200/-1000), number of girlfriends had, and what kind of engineering they study/will study.
The home page of the MSI Consortium is at http://quarl.yi.org/msi/.