Only support to write all valid bits in variable of data type BitFieldMaskDataType|OPC UA Standard|Forum|OPC Foundation

Hi,

Internally in our product we have a set of bit data types (1-8 bits, 16 bits and 32 bits wide). We translate these bit data types to OPC variables with variable type OptionSetValue and data type BitFieldMaskDataType. Internally we have no support to write a portion of the bits of a variable. So, if an OPC client writes only 1 bit (by only setting 1 bit in the validity field) to e.g. a 3 bit variable our OPC server NAK this WriteValue of the write service. Our server implementation requires that the validity field of the BitFieldMaskDataType must match the size of the bit data type, e.g. we expect that 3 bits are set in the validity field if the client writes to a .

My question is what status code we should return to the client for such a WriteValue?