There are four parts to a performance specification. The first is the Operator Type (also called the Product Type); in the NAFS-11 document, 36 operator types are addressed (i.e. HS represents a horizontal slider; C is a casement window; H is a single-, double-, or triple-hung, etc.).
Next is the Performance Class; depending on the referenced version of NAFS, there are either five (for NAFS-05) or four (for NAFS-08 and NAFS-11). When specifying via NAFS-05, the included performance classes are: R, LC, C, HC and AW. When specifying via NAFS-08 or NAFS-11, the included performance classes are: R, LC, CW and AW
The third part is the Performance Grade, stated as a pressure in psf (pounds per square foot). Each Performance Class requires a minimum Performance Grade; for example, an R class window must pass testing for a minimum Performance Grade of 15 psf (720 Pa). More information on minimum gateway test sizes can be found on the Performance Class Overview page on the AAMA website.
The last information is the size tested in the lab to qualify the product for certification. The standard specifies a minimum test size for each Product Type and Performance Class. The sample to be tested must be equal to, or larger than, this size. If the manufacturer plans to certify a particular design in larger sizes, they must test to the largest size they plan to certify and label.