The parameter DataSetOffset with the DataType UInt16 is the offset in bytes inside a NetworkMessage at which the DataSetMessage is located, relative to the beginning of the NetworkMessage.

The default value 0 indicates that the position of the DataSetMessage in a NetworkMessage is not fixed. If the DataSetWriter is disabled and the DataSetOffset is not 0, the valid flag of the DataSetFlags1 in the DataSetMessage header at the offset shall be false.

This parameter should be set if the PayloadHeader flag in the NetworkMessageContentMask is false and therefore the NetworkMessage has a fixed layout.