2.2.3.1.1 Framing Header
The Framing Header is used by all packet types. The syntax of the framing header is defined as follows.
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2 |
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B |
Frame |
PacketID |
PacketLength |
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Reason (optional) |
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B (1 bit): A 1-bit flag. This flag SHOULD be set to 1 if the next packet will be sent immediately after this packet is sent. In this context, "immediately" means that the server does not intentionally introduce a delay (such as a pacing delay) between the transmission of the two packets. In all other cases, the flag MUST be 0.<56>
Frame (7 bits): A 7-bit field. This field MUST have the value 0x24. (If the B and Frame fields are treated as a single byte, the value of this byte will be 0x24 when the B field is 0, and 0xA4 when the B field is 1.)
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Value
Meaning
0x24
If treated as a 7-bit field.
0xA4
If the B and Frame fields are treated as a single byte.
PacketID (1 byte): A 1-byte field that specifies the type of the packet.
PacketLength (2 bytes): A 16-bit unsigned integer field that specifies the size of the MMS data packet (section 2.2.3.1.2), if any, plus the size of the Reason field, if any. Unless otherwise specified, the value of this field MUST be equal to the number of bytes in the packet, counted starting from the end of this field. If neither the MMS data packet nor the Reason field is present, PacketLength MUST be set to 0.
Reason (4 bytes): An optional 32-bit integer field. Unless specified otherwise, if this field is present, its value MUST be set to an HRESULT code, as specified in [MS-ERREF].