To my knowledge, the Da-Lite Cinema Vision 1.3 gain white screen and the Stewart Studiotek 130 white screen are the two ISF "blessed" screens.
http://www.stewartfilm.com/home_cine...theater_9.html
Keep in mind, these recommendations were made more with CRT projectors in mind. The goal was to provide a screen material with the gain that CRT projectors need while avoiding hot-spotting, expanding the viewing angle, and maintaining color uniformity.
Digital projectors are much brighter than CRT's and black levels may suffer with the use of a white screen with gain. Many digital users are willing to sacrifice some color shifting and/or viewing angle to obtain better blacks thru the use of newer hybrid screens (high gain coatings over a gray base material). I dont believe any of these gray screens carry the ISF recommendation as "reference quality" screens.