According to DIN 67510 the luminance at 10 minutes decay time and at 60 minutes decay time are used to form a brief description of the luminance decay performance. Hence we have as follows these notations for the classifications of PSPA and ISO 17398

Luminance Classifications and DIN 67510 notation

Class A    23/3
Class B    50/7
Class C   140/20
Class D   260/35

JALITE additions

Class E 400/55
Class F 520/70
Class G 650/80