Byte swapping is used by the UNIX-style protocols such as TCP/IP, XNS, and IPX. The ordering of a WORD or DWORD is opposite of Intel convention. When creating the property, you should still use the property types of PROP_TYPE_WORD or PROP_TYPE_DWORD, but at attach time, label the instance of the property as swapped. (This is a change from the 1.0 SDK.) See AttachPropertyInstance and AttachPropertyInstanceEx for details on IFLAG_SWAPPED.