EXCEPTIONAL FULL STRIKE = EXFS
When we talk about mint state Morgan Dollars, many dates (especially New Orleans dates from 1886 to 1996) are weakly struck with flat hair over the ear on the obverse and soft breast feathers on the reverse. If you can find a New Orleans and perhaps Carson City date with an exceptional strike, exceptional surface semi proof-like and grade MS-63 or better, that coin is considered an Exceptional First Strike.