Document: FTS-0001
Version: 016
Date: 30-Sep-95
A Basic FidoNet(r) Technical Standard
| Revision 16
Formerly known as FSC001, FSC-0001
| Randy Bush, Pacific Systems Group
| September 30, 1995
C. Presentation Layer : the User from the System's View
1. Presentation Layer Data Definition : the Packed Message
To conserve space and eliminate fields which would be meaningless if
sent (e.g. timesRead), messages are packed for transmission. As this
is a data structure which is actually transferred, its definition is
critical to FidoNet. A packed message has a number of fixed length
fields followed by four null terminated strings.
While most of the string fields in a stored message are fixed length,
to conserve space strings are variable length when in a packet. All
variable length strings are all Null terminated, including especially
the message text.
Packed Message
Offset
dec hex
.-----------------------------------------------.
0 0 | 0 | 2 | 0 | 0 |
+-----------------------+-----------------------+
2 2 | origNode (low order) | origNode (high order) |
+-----------------------+-----------------------+
4 4 | destNode (low order) | destNode (high order) |
+-----------------------+-----------------------+
6 6 | origNet (low order) | origNet (high order) |
+-----------------------+-----------------------+
8 8 | destNet (low order) | destNet (high order) |
+-----------------------+-----------------------+
10 A | Attribute (low order) | Attribute (high order)|
+-----------------------+-----------------------+
12 C | cost (low order) | cost (high order) |
+-----------------------+-----------------------+
14 E | |
~ DateTime ~
| 20 bytes |
+-----------------------+-----------------------+
34 22 | toUserName |
~ max 36 bytes ~
| null terminated |
+-----------------------+-----------------------+
| fromUserName |
~ max 36 bytes ~
| null terminated |
+-----------------------+-----------------------+
| subject |
~ max 72 bytes ~
| null terminated |
+-----------------------+-----------------------+
| text |
~ unbounded ~
| null terminated |
`-----------------------------------------------'
Due to routing, the origin and destination net and node of a packet
are often quite different from those of the messages within it, nor
need the origin and destination nets and nodes of the messages within
a packet be homogenous.
PakdMessage = 02H 00H (* message type, old type-1 obsolete *)
origNode (* of message *)
destNode (* of message *)
origNet (* of message *)
destNet (* of message *)
AttributeWord
cost (* in lowest unit of originator's
currency *)
DateTime (* message body was last edited *)
toUserName{36} (* Null terminated *)
fromUserName{36} (* Null terminated *)
subject{72} (* Null terminated *)
text{unbounded} (* Null terminated *)
