This simple DataType is a subtype of UInt64 and represents a bit mask up to 32 bits where individual bits can be written without modifying the other bits.

The first 32 bits (least significant bits) of the BitFieldMaskDataType represent the bit mask and the second 32 bits represent the validity of the bits in the bit mask. When the Server returns the value to the client, the validity provides information of which bits in the bit mask have a meaning. When the client passes the value to the Server, the validity defines which bits should be written. Only those bits defined in validity are changed in the bit mask, all others stay the same. The BitFieldMaskDataType can be used as DataType in the OptionSetType VariableType

Its representation in the AddressSpace is defined in Table 160.

Table 160 – BitFieldMaskDataType Definition

Attributes	Value
BrowseName	BitFieldMaskDataType