The format of DSS bit masks is a bit more complicated than it used to be. Basically a bit mask is an integer (in SAS useage usually 32 bits in size), each bit of which is intended to be interpreted in a boolean sense. However the dsslib call dssFilterMask() now returns two pointers, onBitMasks and offBitMasks, each of which contains a sequence of masks.
The pointers onBitMasks and offBitMasks are supposed to always be the same size, although there is nothing at the API level to force this to be the case. This is a little unfortunate perhaps and to correct this I have defined in the present module a structure BitMaskT which contains an 'on' mask and an 'off' mask.