A PerfectMatch is a form of context match that compares updated source files to a corresponding set of old bilingual documents rather than to a translation memory. Segment matches, known as PerfectMatch units (XUs), are checked for context, that is, the surrounding entries are checked to ensure that they are the same. They are then extracted from the old bilingual documents and transferred to the updated source files. Because the PerfectMatch segment matching process includes a check for context, XUs typically need no further translation or editing during translation.
[Edited at 2013-06-25 00:46 GMT]
Well, that wouldn't be coming up as "fuzzy" I guess.
[Edited at 2013-06-25 03:15 GMT]