| Document: FSC-0081 Part A
  | Version:  001
  | Date:     01 Mar 1995
  |
  | Mikael St�ldal, 2:201/337

                         A TYPE-3 Packet proposal
                    Mikael St�ldal, 2:201/337@FidoNet


Status of this document
=======================
Copyright (C) 1992-1994 by Mikael St�ldal.

This document may be freely distributed and copied. The standard described
may be implemented by anybody. You may not distribute modified versions of
this document without written permission from the author.

Fido and FidoNet are registered trademarks of Tom Jennings and Fido
Software.


Introduction
============
This is a proposal on a new packet format for use in FidoNet and other FTNs
(FTN = FidoNet Technology Network). This format can be used for both NetMail
(private point-to-point mail) and EchoMail (electronic conferences).

This document defines the transport layer. It also includes a presentation
layer definition, but that can be changed without affecting the transport
layer. It also includes a application layer (stored messages) definition,
but it's not mandatory.

This packet format conforms with FSC-39, rev 4. It has the PktType field in
the header at the same position as TYPE-2 and it contains a capability word
at the same position as TYPE-2+ (but no CW validation copy). The packet
header has also the same size as in TYPE-2. This should make it easy to
implement mail-processors supporting both TYPE-2 and TYPE-3.

This packet format separates the header from the message data and the header
is extensible. A mail processor (the transport layer) doesn't have to look
at the message data.

This format eliminates most kludges currently used in TYPE-2.

This packet format allows multiple AreaTags in EchoMail.

This packet format is much more extensible than TYPE-2 and is probably
easier to implement.

This packet format allows up to 4 GigaBytes large messages and allows binary
data in messages, this makes it possible to implement multimedia
capabilities in the future.


Definitions
===========

Characters
----------
In this document, literal characters are written as two uppercase hexadecimal
(base 16, 0..9A..F) digits following by lowercase h, e.g. "1Fh". The
following abbreviations are used: "NUL" means 00h, "CR" means 0Dh and
"space" means 20h (the quotation marks are not included).


Basic data types
----------------
Name      Length  Description
----------------------------------------------------------------------------
ShortInt    1     8-bit unsigned integer.
Integer     2     16-bit unsigned integer, Intel 8086 byte order.
LongInt     4     32-bit unsigned integer, Intel 8086 byte order.
Byte        1     Field of 8 bits.
Word        2     Field of 16 bits, Intel 8086 byte order.
String[n]   n     Fixed length string of n bytes, NUL-padded.
String{n} max n   Variable length string of max n bytes, NUL-terminated.
                  n includes the terminating NUL.
String            Variable length string, not terminated.


Address
-------
Field      Type            Description                             Range
----------------------------------------------------------------------------
Zone       Integer         Zone address.                          1..65535
Net        Integer         Net address.                           1..65535
Node       Integer         Node address.                          0..65535
Point      Integer         Point address or zero if boss.         0..65535


FTN address in text format
--------------------------
An FTN address in text format must, unless otherwise stated, be in the
Zone:Net/Node[.Point] format, where .Point must be excluded if point is
zero, included otherwise.


TimeStamp
---------
A LongInt which contains the number of seconds since 00:00:00 1st January
1970 UTC.


Organization
------------
An organization is a network such as FidoNet, VirNet, SigNet or InterNet.
It's sometimes called "domain", but I use the term organization to avoid
confusion with InterNet domains.


Reserved
--------
All fields marked "reserved for future extension" must be zeroed when
creating/writing and ignored when reading. They might be defined by future
revisions of this document.


Filenames
=========
It's recommended to use the naming scheme in FTS-LIST, for both NetMail and
EchoMail. There should be no problem with using the same name space for
TYPE-2 and TYPE-3 packets because the packet headers are enough compatible.


Packet format
=============
Packet header
Zero or any number of data records.
00h 00h

The first two bytes of a data record is used to check for the end of a
packet. If both are zero, the end is reached (and the rest, if any, should
be ignored).


Packet header
=============
Field      Type            Description
----------------------------------------------------------------------------
PktOrig    Address         The node who created this packet.
PktDest    Address         The node who should receive this packet.
SubType    Integer         Packet contents (see below).
PktType    Integer         Always 3.
PktDate    TimeStamp       When the packet was created.
ProdCode   Integer         FTSC Product Code. 
                           Programs without Product Code must use 65535.
MajorVer   ShortInt        Major product version.
MinorVer   ShortInt        Minor product version.
Org        String[16]      Organization (see below).
CapWord    Word            Capability Word (see FSC-39).
Password   String[8]       Packet password.
ExtraInfo  String[4]       Reserved for future extension.


SubType
-------
Defines what the packet contains.

If this field is zero, data record is defined by the "Packed message" part
of this document. If this field is non-zero, data record is not defined by
this document.

This field can be used for two things. The first is to define new packet
types without having to use a new packet header. The second is to allow
distribution of other things than Email.


Organization
------------
This field contains the name of the organization the packet travels in. This
field applies to both PktOrig and PktDest since packets are
intra-organization.


Packed message
==============
The messages should be in chronological order in a packet.

Field      Type              Description
----------------------------------------------------------------------------
HeadSize   Integer           Size of the message header (see below).
MsgFlags   Word              Message flags (see below).
MsgDate    TimeStamp         When the message was created.
MsgID      LongInt           Unique message identifier (see below).
ReplyID    LongInt           Reply linkage information (see below).
MsgLength  LongInt           Size of MsgData.
MsgOrig    Address           The node who created this message.
MsgDest    Address           The node who should receive this message.
CharSet    ShortInt          Character set (see below).
MsgType    ShortInt          Type of MsgData (see below).
Area       String{255}       AreaTag(s) (see below).
OrigAddr   String{255}       Origin address in text format (see below).
ReplyAddr  String{255}       Reply linkage information (see below).
FromUser   String{255}       Who wrote this message?
ToUser     String{255}       To whom?
Subject    String{255}       Subject or one filename
                             (for file attaches and requests).
Path       String{65535}     Path (see below).
HeadExt    String            Header extension fields (see below).
MsgData    String            Message data (see below).


HeadSize
--------
The total size of the message header (all fields except MsgData). Since this
is an Integer, the header can't be bigger than 65535 bytes and Path can never
reach it's maximum length (how big it can be depends on how big the rest of
the header is).


Message flags
-------------
Bit  Flag          Meaning
----------------------------------------------------------------------------
 0   Pvt           Private message.
 1   File          File attach message.
 2   FileReq       File request message.
 3   UpdReq        File update request message.
 4   Direct        Do not route this message.
 5   Crash         High priority mail.
 6   Hold          Hold for pickup.
 7   IMM           Immediate mail (highest priority).
 8   RRQ           Return receipt request (see below).
 9   CRQ           Confirm receipt request (see below).
10   IRR           Is return receipt (see below).
11   Machine       Message to a program (see below).
12   NoForCC       CC in NetMail, NoForward in EchoMail (see below).
13   Permanent     Message must not be purged by age (see below).
14   Foreign       Message is from another organization.
15   reserved      Reserved for future extension.


RRQ, CRQ and IRR
----------------
The RRQ and CRQ flags without IRR is used to ask the software at the final
destination to generate a receipt message to the sender. The receipt to an
RRQ flagged message must be generated when the message is received, and
this receipt must have the IRR and RRQ flags set. The receipt to a CRQ
flagged message must be generated when it has been read by its addressee,
and this receipt must have the IRR and CRQ flags set.

A receipt must have the ReplyAddr and ReplyID fields set as if it was a
reply to the original message.

It's up to each network's policy to decide if all systems must support this,
no system are allowed to support this or all systems are allowed but not
forced to support this.


Machine
-------
The Machine flag indicates that this message is addressed to a program and
not a human. A mail processor should store such messages as defined in the
"Stored message" section later in this document so the program doesn't have
to support 4711 different message base formats. The name of the program must
be in the ToUser field.


Carbon Copy
-----------
The CC flag is used for sending a NetMail message to several nodes. Which
nodes is determined by the MsgDest field.

If the message is addressed to a Zone Coordinator, the message is destined
for all nodes in that zone. If the message is addressed to a Region
Coordinator, the message is destined for all nodes in that region. If the
message is addressed to a Net Coordinator, the message is destined for all
nodes in that net. If the message is addressed to a HUB, the message is
destined for all nodes under that HUB.

If the receiver of a CC message have other coordinators (or HUBs) below, it
must send the message to them as CC's too.

If the ToUser field is empty the message is considered to be addressed to
the SysOp and the name is taken from the nodelist (or set to "SysOp"). This
must be done by the system immediate before the destination (usually the
destination's HUB).


Permanent
---------
This flag indicates that the message must not be removed when old messages
is cleaned out.

A new message with this flag automatically erase an old message with the
same data in the Subject field. If you want to erase a permanent message
without replacing it with a new, then post an empty message with the
Permanent flag and the appropriate data in the Subject field.

This flag can only be used in EchoMail.

 
OrigAddr
--------
This field must contain the true origin address of the message in text
format followed by an "@" (40h) and the name of the originating
organization.


Message ID
----------
The origin address and MsgID fields are used as a unique message identifier.
How the MsgID field is generated is left to the implementor, but it must be
unique for each message generated on a given node in at least three years.
MsgID must normally not be zero, zero is used to indicate lack of
Message-ID.  With this system these two fields together is unique for every
message, and can be used for duplicate detection and other things.


Reply linkage information
-------------------------
In a reply the ReplyAddr and ReplyID fields must be identical to the origin
address, and MsgID fields in the replied message. A message which is not a
reply must have these fields empty. Use the ReplyAddr field to check this.


Area
----
A list of one or more AreaTags in EchoMail, just a NUL in NetMail. If the
list contains more than one tag, they are separated by space. 00h through
1Fh are not allowed in this field (except NUL as the terminator).


Path
----
This field contains a series of addresses separated by space. The first
system must place its address in this field and every system that routes the
message must add its address to this field,

Note that the first address in this field and the address in the MsgOrig
field doesn't have to be the same.

The first address must be the origin address in this format:
zone:net/node.point@organization

In the other addresses organization, zone, net and node must be omitted if
same as the previous address.

The other addresses must be in one of these formats:
zone:net/node.point@organization
zone:net/node.point
net/node.point
node.point
.point

.point must be excluded if point is zero, except when .0 stands alone.

Example:
1:123/324@FidoNet sends a routed NetMail message to 2:224/546.5; 1:123/300,
1:123/0, 1:12/0, 1:1/2, 2:22/888, 2:22/0, 2:224/0, 2:224/546 and 2:224/546.3
routes the message (in that order). The path field must in this case be
"1:123/324@FidoNet 300 0 12/0 1/2 2:22/888 0 224/0 546 .3" when
2:224/546.5 receives the message. Note that the message is routed via a
point, that might not be so common but it's technically possible.

In EchoMail, the Path field can also contain addresses suffixed by an
exclamation mark ("!", 21h). This means that that node hasn't routed the
message, but the message has been sent to him. Similar to SEEN-BY's in
FTS-4. However, this should only be used when necessary.

Never send an EchoMail message to a node listed in the Path field; regardless
if the address is suffixed by an exclamation mark or not.

If the message originates in a non-FTN organization, the name of the origin
organization prefixed by an "@" (40h) must be placed before the address of
the gateway. In such cases there may also be some other FTN addresses before
the non-FTN organization name if the message have travelled from an FTN, via
a non-FTN and to a FTN again.

Example:
someone@one.two.three in InterNet sends a routed NetMail message to
1:222/345 in FidoNet via the gateway 1:222/111 and 1:222/300. The path field
must in this case be "@InterNet 1:222/111@FidoNet 300" when 2:222/345
receives the message.

If there's not enough room to update the Path field (add what you should and
have at least two bytes left), put a single "$" (24h) in it instead (and a
space between it and the last address).

This field has the same format as the PTH line specified in FSC-44 (except
the "$"). Read FSC-44 for more information.


HeadExt
-------
This field contains zero or more NUL-terminated strings. The end of this
field can be determined by the HeadSize field, but there must be a NUL after
the last string anyway. If there are no strings here, there must not be any
NUL either.

Each string here is a header extension field. A header extension field
contains a keyword followed by a space and some data. A header extension
field can contain only a keyword with no data, in such case a space must not
be used either.


Inter-organization messages
---------------------------
To send a message to an other organization place the final address in text
format followed by an "@" (40h) and the name of the destination organization
in a header extension field with the keyword "DEST" and address the message
to a gateway.

If the message must travel over more than one organization-border, the
addresses to each gateway can be pointed out by header extension fields with
the keyword "ROUTE". ROUTE fields contains addresses in the same format as
DEST lines. The order of the ROUTE fields is important and the DEST field
must be after the ROUTE field(s). When the gateway pointed by a ROUTE field
processes the message it must change "ROUTE" to "ROUTD".

Note: The gateway from your organization are pointed out by the MsgDest
field so there must not be a ROUTE field for that gateway.

Example:
You are 34:65/12@StrangeNet and want to send a message to
someone@one.two.three in InterNet. StrangeNet hasn't got any gateway to
InterNet, but FidoNet has gateways to both StrangeNet and InterNet. In that
case the message may have the following header extension fields:
ROUTE 1:1/20@FidoNet
DEST someone@one.two.three@InterNet

Messages from other organizations (NetMail or EchoMail doesn't matter) must
have their origin addresses (including @organization as mentioned before)
stored in the OrigAddr field and the Foreign flag set.  The MsgOrig field in
the header must contain the address of a bidirectional gateway.

The MsgID field must be generated using the message-ID in the originating
organization, if that is possible.  If the originating network doesn't have
any message-ID that can be used to create the MsgID field, the MsgID field
must be set to zero. If two identical messages (with identical message-ID)
enters an FTN organization at two different gateways, they should get the
same MsgID. The same counts for ReplyID. ReplyAddr must also be transferred
if present in the original message.

If the other organization uses a message-ID format that can't be
transparently mapped to MsgID, a ORIGID header extension field is created
with a direct copy of the original message-ID (both address and serial
number). The same is done with reply-linkage information in a ORIGREF header
extension field. This information is used if the message should be gated
back to the original network.
Example with message from InterNet:
ORIGID <abcd43kxz@somewhere.org>
ORIGREF <bcdef43gkrt@elsewhere.org>


Message routing
---------------
The transport layer (including intermediate systems (systems handling
in-transit messages)) are not allowed to change anything in the MsgDate,
MsgID, ReplyID, MsgLength, CharSet, MsgType, OrigAddr, ReplyAddr, FromUser,
ToUser, Subject and MsgData fields. No flags may be changed by the transport
layer except the Foreign flag at gateways. The only exception is if the
message have to be converted to another packet type.

An intermediate system must update the Path field, both in NetMail and
EchoMail.

In EchoMail, the Area field may be changed.

An intermediate system are allowed to add or change header extension fields.

An intermediate system can add a header extension field with the keyword
"Via". The Via field contains information about the system and when it
processed the message. It's up to each network's policy to decide if this is
allowed in NetMail, EchoMail or both.

If the header is changed, the HeadSize field must be updated.


EchoMail
--------
This section lists the changes to FTS-4 needed to implement EchoMail with
this packet format.

SEEN-BY lines are not to be used. The Path field is used instead of PATH
lines. The Area field is used instead of the AREA line. The MsgOrig and
OrigAddr fields must contain the origin addresses of the message. A
unaddressed EchoMail message must have the ToUser field empty, unless there
is a good reason to put something there.

The MsgDest field must be used as in NetMail. If you receive a EchoMail
message not addressed to any of you addresses, you must handle it as
in-transit NetMail. This makes it possible to route EchoMail through nodes
not connected to the area. This can be performed inter-organization as well.

Since the lack of complete SEEN-BY's, an EchoMail processor must use the
single-pass technique. That means that it must export a message to all its
downlinks at the same time as it tosses the message, before it goes into the
local message base (it doesn't even have to get there if the area is
pass-through). With this technique the tosser can do what ever it wants with
the message before it stores it in the local message base since the message
will never get out of it again (except when a rescan function is invoked,
but the requesting system will have to stand that).

A system which receives an EchoMail message with the NoForward flag set must
not export that message. This flag is indented for EchoMail processors with
a rescan function, all rescanned messages must have the NoForward flag set.

The tear and origin lines have no technical meaning (the origin address is
stored elsewhere) so no program is forced to create them. Additionally, a
program must not require them.

To distinguish EchoMail from NetMail, check the Area field. NetMail messages
have empty Area fields.

Cross-posting a message in several areas is preformed by storing multiple
AreaTags in the Area field. If some of your downlinks don't have all the
areas listed in the Area field then you must remove the AreaTags for the
areas they don't have. All copies must still have the same MsgID. If you
receive several messages with the same MsgID but different Area then you
must join them into a single message and put all different AreaTags in the
Area field (but not the same twice). Compare all fields in the header up to
and including Subject (except Area) and not only MsgID.

When preforming dupchecking with MsgID, compare all fields in the header up
to and including Subject and not only MsgID.


CharSet
-------

Value    Character set
----------------------------------------------------------------------------
1..99    ISO 8859 (8 bit)
100      ISO 10646 16 bit (Unicode)
101..149 Reserved for other 16 bit character sets
150      ISO 10646 32 bit
151      PC8-437 (The Original)
152      PC8-850 (Multilingual)
153      PC8-852 (Slavic)
154      PC8-860 (Portuguese)
155      PC8-863 (Canadian-French)
156      PC8-865 (Nordic)
157..199 Reserved for other 8 bit character sets
200..255 reserved

PC8 means IBM's codepage (8 bit).

CharSet=1 means ISO 8859-1 (Latin-1), CharSet=2 means ISO 8859-2 and so on.

CharSet concerns FromUser, ToUser and Subject. It may also concern MsgData.

Combined characters are built by 02h followed by a modifier and the base
character. If you can't display the combined character, just ignore the
modifier and display the base character unmodified. A combined character
contains three bytes and are counted as three bytes. See FSC-51 for more
information on this. There are a few things in FSC-51 that doesn't apply to
this format: this method is allowed on all 8 bit character sets, not only
Latin-1, and the byte values 80h through 9Fh are allowed. This can only be
used for 8 bit character sets. Combined character can be used in FromUser,
ToUser and Subject, it may also be allowed in MsgData.


MsgLength, MsgType and MsgData
------------------------------
If the MsgData field contains nothing (MsgLength is zero), it's an empty
message. An empty message must be forwarded and routed as any other message.
An empty message must not be stored in the local message base (but read
about the Permanent flag).

If MsgType is zero, MsgData is defined by the "Message text" part of
this document.

If MsgType is non-zero, the MsgData field is not defined by this document.


Message text
============
This part defines the presentation layer.

The CharSet field in the header concerns the message text except binary
extension fields. Combined characters can be used in the message text except
in binary extension fields.

If a 16 or 32 bit character set is used all characters are two or four bytes
so all control codes must be prefixed by 00h or 00h 00h 00h. The bytes alone
can be in printable character. The length of binary extension fields is
still counted in bytes.

All 256 byte values (including NUL) are accepted in the message text. 00h
through 1Fh are control codes and must not be used to represent printable
characters.

A paragraph (also called "physical line") is ended with CR.

8Dh (sometimes called "Soft CR") must not be used as a line separator since
it represents a printable character in some character sets.

01h first at a physical line (i.e. the first character of the message text
or the character immediately after a CR) means that this line is a extension
line. See below for more information.

00h first at a physical line (except in another binary extension field)
indicates the start of an long binary extension field. 00h is followed by a
LongInt and up to almost 4 GigaBytes of binary data. A binary extension field
is not terminated in any way, it's length is stored in the LongInt (the 00h
and the LongInt itself is not included in the length).

15h first at a physical line (except in another binary extension field)
indicates the start of an short binary extension field. 15h is followed by a
ShortInt and up to 255 bytes of binary data. A binary extension field is not
terminated in any way, it's length is stored in the ShortInt (the 15h and
the Integer itself is not included in the length).

Attributes:
03h = Turn off all attributes
04h = Bold
05h = Italic
06h = Underline
17h = All caps (lower case letters as small caps)
19h = Subscript
1Ah = Superscript
1Ch = Blinking
1Dh = Inverted
1Eh = Concealed
Subscript automatically turns off superscript and vice versa. All other
attributes can be used together. If an attribute already is on, it's turned
off by the same code again. If your system doesn't support an attribute,
just ignore it. CR turns off all attributes.

To quote a message begin a physical line with 1Fh followed by the initials
of the person you are quoting and another 1Fh. Use just two 1Fh if you don't
want any initials. Successive quoting is marked with more 1Fh:s immediate
after the two first ones. A quote is ended with CR. It's up to each
implementor to decide how to display quoted text, but it must be possible to
distinguish it from normal text. It's recommended to display it in another
color if possible. You must translate the quote to the same character set
used in the rest of the message.

The last paragraph of the message text must be terminated by a CR (i.e. the
last character of the message text must be a CR unless a binary extension
field is last).


Extension lines
---------------
An extension line contains a keyword followed by a space and some data. A
extension line can contain only a keyword with no data, in such case a space
must not be used either. An extension line is ended like a paragraph.

Extension lines may not contain 00h through 1Fh. If you want binary data,
use a binary extension field instead.

Extension lines are control information any should not be displayed to the
user. If you want "hidden lines", then use the Concealed attribute rather
than an extension line.

Information that is relevant for the transport layer must be placed in a
header extension field rather than in an extension line.

Extension lines can be useful for describing a binary extension field.


Currently defined extension lines
---------------------------------
A extension line with the keyword FILE is used for sending files embedded in
the message text. The keyword is followed by a eight digit uppercase
hexadecimal number containing a TimeStamp for the file, a space and the
filename. The filename can contain all chars valid for extension lines
(including space) and must be at least 1 char and at most 255 chars. The
file is stored in a binary extension field immediate after the FILE line.
Examples:
FILE AB34F657 FILE.EXT
FILE 1234ABCD This is a filename


Stored message
==============
This is a description of the application layer, the local message base.

It is recommended to use this format to store NetMail messages locally. It
can also be used for EchoMail, but that's not necessary.

Each message is stored as a single file which must have a hexadecimal number
from 00000001 to FFFFFFFF as the base name and the extension MS3 (to
distinguish from TYPE-2 stored messages).

Messages can be stored in two ways. Either the same way as TYPE-2 with one
directory for each area (including NetMail), in that case the Area field
must be empty in all messages. Or all messages in the same directory with
the area field used to indicate what/which area the message belongs to (or
empty to indicate NetMail). The second format is useful if you normally store
EchoMail in an other format and only use this format for messages with the
Machine flag.


Field      Type              Description
----------------------------------------------------------------------------
SRdate     TimeStamp         When the message was sent or received
                             (see below).
ReplyTo    LongInt           Message which this replies (see below).
Reply1st   LongInt           First reply to this message (see below).
ReplyNext  LongInt           Next reply to this message (see below).
LocalFlags Word              Local flags (see below).
Cost       Integer           Cost of sending in the lowest currency unit.
HeadSize   Integer           Size of the message header (see below).
MsgFlags   Word              Same as packed message.
MsgDate    TimeStamp         Same as packed message.
MsgID      LongInt           Same as packed message.
ReplyID    LongInt           Same as packed message.
MsgLength  LongInt           Same as packed message.
MsgOrig    Address           Same as packed message.
MsgDest    Address           Same as packed message.
CharSet    ShortInt          Same as packed message.
MsgType    ShortInt          Same as packed message.
Area       String{255}       AreaTag(s) (see above).
OrigAddr   String{255}       Same as packed message.
ReplyAddr  String{255}       Same as packed message.
FromUser   String{255}       Same as packed message.
ToUser     String{255}       Same as packed message.
Subject    String{255}       Same as packed message.
Path       String{65535}     Path (see below).
HeadExt    String            Same as packed message.
MsgData    String            Same as packed message.


HeadSize
--------
The total size of the message header (all fields except MsgData). Since this
is an Integer, the header can't be bigger than 65535 bytes and Path can
never reach it's maximum length (how big it can be depends on how big the
rest of the header is).

Please note that this won't contain the same value when the same message is
placed in a packet because SRdate, LocalFlags, ReplyTo, Areply and Cost
isn't included then and Area might not have the same length.


Local flags
-----------
Bit  Flag          Meaning
----------------------------------------------------------------------------
0    Local         Message is created locally.
1    InTransit     Message is not destined for this system.
2    Orphan        Unknown destination.
3    KillSent      Remove message after it has been sent.
4    DelSent       Delete attached file(s) after they have been sent.
5    TruncSent     Truncate attached file(s) after they have been sent.
6    Sent          Message has been sent.
7    Read          Message has been read by the SysOp.
8    Rcvd          Message has been read by its addressee.
9    Lock          Lock the message for further access.
10   DontSend      Do not send the actual message but send attached files,
                   make file requests and poll the destination if necessary.
11   unused        Reserved for future extension.
12   unused        Reserved for future extension.
13   unused        Reserved for future extension.
14   unused        Reserved for future extension.
15   unused        Reserved for future extension.

Note that "sent" also can mean "picked up".


SRdate
------
The meaning of this field is determined by the Local and Sent flags.
Local but not Sent: Meaningless, must be zero.
Local and Sent: When the message was sent or picked up.
Not Local: When the message arrived to this system.


Reply linking
-------------
The ReplyTo field points at the message which the current message replies.
The Reply1st field points at the first reply to the current message (the
reply with lowest number); a messages with no replies must have this field
set to zero. The ReplyNext field points at the next reply the same message
as the current message; this field must be zero if there are no more replies
to the message the current message. A message which is no reply must have
the ReplyTo and ReplyNext fields set to zero.

With this system there is possible to keep track of an unlimited number of
replies to any message.


Path
----
If the local flag is set, this field must be empty. It's the mail processors
responsibility to insert the address here when placing the message in a
packet.

When the mail processor tosses an incoming message, it must copy the Path
field from the packet.


Control file
------------
In each message directory (both EchoMail and NetMail) there must be a file
named LASTREAD. When an area is renumbered, this file must be updated.

Field      Type            Description
----------------------------------------------------------------------------
LastRead   LongInt         The last message read.
HighRead   LongInt         The highest message read.
HighWater  LongInt         High-water mark (only used with EchoMail).
                           This field is used by the EchoMail processor to
                           store the number of the last scanned message.


Notes
=====
If you are implementing this and something confuses you, ask someone who
knows. Please don't guess how it should be.


Credits
=======
Thanks to Krister Hansson-Renuad, Johan Olofsson, Nils Hammar, Jonas
H�gstr�m, Mats Gefvert and others who have helped me developing this.




  | Document: FSC-0081 Part B
  | Version:  001
  | Date:     01 Mar 1995
  |
  | Mikael St�ldal, 2:201/337

           How the TYPE-3 packet format can coexist with TYPE-2
                           in the same network.
                    Mikael St�ldal, 2:201/337@FidoNet


Introduction
============
This document describes how to convert between the old TYPE-2 format and the
new TYPE-3 format. The TYPE-2 format is documented in FTS-1 and FSC-39. This
document only describes how to convert the packed messages, it should be
obvious how to deal with the packet header if you read FSC-39 and the TYPE-3
specification.

Read FSC-39, rev 4 for information on how to determine which format to use
when sending packets to other nodes.

An FTN address in text format must, unless otherwise stated, be in the
Zone:Net/Node[.Point] format, where .Point must be excluded if point is
zero, included otherwise.

The field names in FTS-1 are used.

"kludge" means a line beginning with 01h in TYPE-2 messages.


TYPE-2 => TYPE-3
================

General
-------
In Attribute, the Private, Crash, FileAttach, HoldForPickup, FileRequest,
and FileUpdateReq bits is transferred to the MsgFlags field. The other bits
are ignored. If a FLAGS kludge exists, it's checked for DIR, IMM, MCH, RRQ,
CFM and PER which are used to set Direct, IMM, Machine, RRQ, CRQ and
Permanent respectively. If IRR or ICR exists in a FLAGS kludge, they are used
to set RRQ/IRR or CRQ/IRR.

DateTime is used to create the MsgDate field. If that fails, the MsgDate
field is set to the current time.

If any FROMUSER3, TOUSER3 and/or SUBJECT3 kludges exist, they are used to
create the FromUser, ToUser and Subject fields. Otherwise fromUserName,
toUserName and subject are used.

If a TYPE3 kludge exists, it's used to create the MsgType and CharSet
fields.

If any  CHRS, CHARSET or I51 kludges exist, they are used to create the
CharSet field. I51 means CharSet=1. If any CHRS or CHARSET kludge indicates
a character set not supported by TYPE-3, the message must be converted. If
no such kludge exist, the CharSet field is set to 0. This is not performed
if a TYPE3 kludge exists.

If a PTH kludge exist, it's used to create the Path field. Otherwise, the
Path field is set to your address only.

If a MSGID kludge exists, the serial number is used to create the MsgID
field. Otherwise it's set to null.

If an ORIG kludge exists, it's used to create the OrigAddr field, otherwise
the address in the MSGID kludge is used. If the address doesn't contain
organization, the name of your organization is added. If the ORIG kludge
indicates that the message comes from another organization, set the Foreign
flag. If non of these kludges exists the OrigAddr field is set to null.

If a REPLY kludge exists, the address is used to create the ReplyAddr field
and the serial number is used to create the ReplyID field.

A split message (containing a SPLIT3 kludge) is rejoined.

If a TYPE3 kludge exists and contains UU, the text after it are UUdecoded
and placed in the MsgData field.

Any quoted text in the FSC-32 format is converted to the TYPE-3 format.

Any binary extension fields (BIN3 kludges) are decoded.

Any FMPT, TOPT, INTL, BIN3, SPLIT3, CHARSET, CHRS, I51, ORIG, MSGID, REPLY,
EID, PTH, PATH, RESCANNED and TYPE3 kludges are removed from the message
text. Any other kludges are converted to extension lines, except kludges
before any TYPE3 kludge which are converted to header extension fields.

destNode, destNet, together with any TOPT and INTL kludges are used to create
the MsgDest field. If TOPT is missing, the Point field is set to 0. If INTL
is missing, the Zone field is set to your zone.

If a DEST kludge with organization (called "domain" in FSC-58, rev 2)
exists, the message is considered to be inter-organization and the DEST
kludge is converted to a DEST header extension field. If a DEST kludge
without organization exists, it's removed from the message text. In
inter-organization messages, any ROUTE and ROUTD kludges are converted to
header extension fields. However, a ROUTE kludge with the same address as
MsgDest (check the organization too) must be removed.


NetMail only
------------
origNode, origNet, together with any FMPT and INTL kludges are used to create
the MsgOrig field. If FMPT is missing, the Point field is set to 0. If INTL
is missing, the Zone field is set to your zone.


EchoMail only
-------------
The address in the Origin line is used to create the MsgOrig field. If no
valid origin line exists, it is created as in NetMail.

The AREA line is used to create the Area field.

The AREA and SEEN-BY lines are removed from the message text.

If a RESCANNED kludge exists, the NoForward flag is set.


TYPE-3 => TYPE-2
================

General
-------
In MsgFlags, the Pvt, Crash, File, Hold, FileReq and UpdReq bits is
transferred to the Attribute field. If Direct, IMM, Machine and/or Permanent
is set, a FLAGS kludge is created and set to DIR, IMM, MCH and/or PER
respectively. If RRQ but not IRR is set, RRQ is added to the FLAGS kludge. If
CRQ but not IRR is set, CFM is added to the FLAGS kludge. If RRQ and IRR is
set, IRR is added to the FLAGS kludge. If CRQ and IRR is set, ICR is added
to the FLAGS kludge. If IRR but not RRQ or CRQ is set, it's an error and
should be ignored.

MsgDate is used to create the DateTime field. It must be set to the primary
format specified in FTS-1.

FromUser, ToUser and Subject are transferred to the fromUserName, toUserName
and subject fields. If they are too long, they are truncated. If any of them
are too long, the whole field is put in a FROMUSER3, TOUSER3 and/or SUBJECT3
kludge.

If CharSet is set to 1, a "CHRS: LATIN-1 2" kludge is created. If CharSet is
set to 151, a "CHRS: IBMPC 2" kludge is created.

If the message originates in another organization (use the Foreign flag to
check), the OrigAddr field is used to create an ORIG kludge.

MsgOrig is used to create the origNode and origNet fields. If Point is
nonzero, a FMPT kludge must be created. An INTL kludge must always be
created.

MsgDest is used to create the destNode and destNet fields. If Point is
nonzero, a TOPT kludge must be created. An INTL kludge must always be
created.

If MsgID is nonzero, OrigAddr and MsgID is used to create a MSGID kludge.
The hexadecimal serial number must be in lowercase.

If ReplyAddr is nonzero, ReplyAddr and ReplyID is used to create a REPLY
kludge. The hexadecimal serial number must be in lowercase.

Path is used to create a PTH kludge. This kludge must be the last one before
any kludges coming from header extension fields.

A TYPE3 kludge is always created, it contains the value of MsgType in
decimal followed by the value of CharSet in decimal. If the whole MsgData is
UUencoded (as described later), the values must be followed by "UU". E.g.
TYPE3 0 34
TYPE3 1 123 UU

All other kludges kludges mentioned here must be before the TYPE3 kludge.
Everything after the TYPE3 kludge is from MsgData, except Origin, SEEN-BY
and PATH in EchoMail.

Any header extension fields are converted to kludges. They must be immediate
before the TYPE3 kludge.

If MsgType is nonzero or CharSet indicates a 16- or 32-bit character set,
the whole MsgData is UUencoded immediate after the TYPE3 kludge. The first
line must be "begin 666 TYPE3" and the last line must be "end". It's
possible to do this with all messages, but that will make it impossible to
read them when in TYPE-2 format. Here is an example:
begin 666 TYPE3
MX.=E!/\#CG$13<92M*A7V][HV%;+\EHS?HTD=\?,QGP JT"R1D6 7:@2S=Z8
M5?4(%E>RG;(D#=NBD(/U*QZ&5@&I#5Y',GH0WN1ORH!-M%DJ[1"H%#*M9R#]
MUH[M13O:BHW<LM0I@RQJ"P*/"?:SPYOA9;I_4M16E7//<T,+)B]($"X)ANGY
' +]"
end

Any extension lines are converted to kludges. They must be after the TYPE3
kludge. This is not performed if the whole MsgData is UUencoded.

Any quoted text is converted to the FSC-32 format. This is not performed if
the whole MsgData is UUencoded.

Any binary extension fields are UUencoded and put behind BIN3 kludges. The
first line must be "begin 666 short" or "begin 666 long" depending on if
it's a short or long binary extension field. The last line must be "end".
Note that this must be done before any splitting and it's possible to split
a message in the middle of an binary extension field. This is not performed
if the whole MsgData is UUencoded. Here is an example (all lines must have
the kludge char 01h first):
BIN3 begin 666 short
BIN3 MX.=E!/\#CG$13<92M*A7V][HV%;+\EHS?HTD=\?,QGP JT"R1D6 7:@2S=Z8
BIN3 M5?4(%E>RG;(D#=NBD(/U*QZ&5@&I#5Y',GH0WN1ORH!-M%DJ[1"H%#*M9R#]
BIN3 MUH[M13O:BHW<LM0I@RQJ"P*/"?:SPYOA9;I_4M16E7//<T,+)B]($"X)ANGY
BIN3 ' +]"
BIN3 end

If the message is larger than 64 KB, it's split in several smaller
messages. All kludges mentioned in this document except MSGID and REPLY must
be in all parts. MSGID and REPLY must only be in the first part. Kludges not
mentioned in this document (those coming from extension lines) are treated
as normal text. All parts have a SPLIT3 kludge which contains the MSGID
followed by a space, the part's number, a slash ("/", 2Fh) and the number of
parts. The SPLIT3 kludge must be the first kludge except INTL, FMPT and
TOPT. In all parts, a space, a left parenthesis, the part's number, a slash
the number of parts and a right parenthesis is added to the subject field; the
last chars of it are overwritten if there isn't enough room. If no MSGID
exists because MsgID was zero, the message comes from TYPE-2 and should not
be larger than 64 KB; if it is, it should not be split. Note: you may use
a smaller maxlength than 64 KB (such as 16 KB). All parts must be in the
right order immediately after each other in the same packet or the rejoining
may not work.
Example:
Subject: Hello boys!
FMPT 5
MSGID: 1:234/567.5 12345678
REPLY: 2:345/678 23456789
CHRS: IBMPC 2
          |
          V
Subject: Hello boys! (1/3)
FMPT 5
SPLIT3 1:234/567.5 12345678 1/3
MSGID: 1:234/567.5 12345678
REPLY: 2:345/678 23456789
CHRS: IBMPC 2
          +
Subject: Hello boys! (2/3)
FMPT 5
SPLIT3 1:234/567.5 12345678 2/3
CHRS: IBMPC 2
          +
Subject: Hello boys! (3/3)
FMPT 5
SPLIT3 1:234/567.5 12345678 3/3
CHRS: IBMPC 2


EchoMail only
-------------
Area is used to create a AREA line. If Area contains multiple AreaTags, one
message for each area are created.

If the NoForward flag is set, a RESCANNED kludge is created.

If no origin line exist an origin line with only address are created and the
address is set to MsgOrig. No search for Origin is performed if the whole
MsgData is UUencoded.
Example:
 * Origin: (1:234/567)

Create SEEN-BY line(s) with all addresses in Path after the last zone change
that isn't points. Including those with "!" after.

Create PATH line(s) with all addresses in Path after the last zone change
that isn't points. Except those with "!" after.