The inversion mask that is applied to the status match
process. Those relevant bits in the received packet
status that correspond to bits cleared in this mask
must all be equal to their corresponding bits in the
filterPktStatus object for the packet to be accepted.
In addition, at least one of those relevant bits in the
received packet status that correspond to bits set in
this mask must be different to its corresponding bit
in the filterPktStatus object for the packet to be
accepted.
For the purposes of the matching algorithm, if the
associated filterPktStatus object or a packet status
is longer than this mask, this mask is conceptually
extended with '0' bits until it reaches the longer of
the lengths of the filterPktStatus object and the
packet status.
This object may not be modified if the associated
filterStatus object is equal to valid(1).