2.1 Common Base Types
This section contains commonly used primitive data types.
The use of the Interface Definition Language (IDL) implies RPC marshaling unless custom marshaling is specified.
Unless explicitly noted in this document, any integer, either signed or unsigned, is in memory order before RPC marshalling. It is implementation dependent<1> whether the memory order is little-endian or big-endian.
For packets, the bit numbering convention followed is the same as that used in RFCs, namely: the high (most significant) bit of the first byte to hit the wire is in packet bit 0, and the low bit of the last byte to hit the wire is in packet bit 31 (so that the bits are shown from left-to-right in the order they naturally appear over the network).
Figure 1: Packet byte/bit order
Unless otherwise specified, the bytes of a multi-byte integer field are assumed to be transmitted in big-endian order, also referred to as Network Byte Order. That is, if the packet shown above represented a 32-bit integer, then Byte 1 would be its high-order byte and Byte 4 its low-order byte. Certain protocols use little-endian order, as specified in the corresponding technical documents; for example, [MS-SMB2].