The mask that is applied to the match process. After adjusting this mask for the offset, only those bits in the received packet that correspond to bits set in this mask are relevant for further processing by the match algorithm. The offset is applied to filterPktDataMask in the same way it is applied to the filter. For the purposes of the matching algorithm, if the associated filterPktData object is longer than this mask, this mask is conceptually extended with '1' bits until it reaches the length of the filterPktData object. This object may not be modified if the associated filterStatus object is equal to valid(1).