Info on Heidelburg CIP3 PPF ink zone values

Hello,

I'm trying to locate information about the private extensions by Heidelburg for CIP3 PPF ink coverage values.

Specifically, what the units are for the the ink coverage values.

/HDMZoneCoverageValue [0.33474 0.39165 0.25622 0.6038 1.95711 0.39221 0.25622 0.33306 0.68467 0.51194 0.70436 2.00998 0.41616 0.25783 0.2683 0.1547 ] def

Anyone know?