There should be discussion regarding non-standard ports for email tunneling since many ISPs block the standard port, and it is not unheard of for fido nodes to run their own email servers.
Also for discussion... IEM vs EMA flags. Are they the same?
Additions/Changes are marked with ">" in column 1.
This document is a Fidonet Technical Standard (FTS) - it specifies the current technical requirements and recommendations for FTN software developers, coordinators and sysops of the Fidonet network and other networks using FTN technology.
This document is released to the public domain, and may be used, copied or modified for any purpose whatever.
Abstract --------
Nodelist flags extend the basic nodelist format described in FTS-5000, allowing a node to provide detailed information of its operation and capabilities.
Contents --------
1. Introduction 2. Supersessions 3. Purpose 4. Syntax 5. Normal flags 5.1 Operating Condition Flags 5.2 Modem Connection Protocol Flags 5.3 Session Level Error-correction and Compression Flags 5.4 File/Update Request Flags 5.5 Gateway Flag 5.6 Mail Period Flags 5.7 System Online Flags 5.8 ISDN Capability Flags 5.9 Internet Capabilities 5.10 Robot flags 5.11 Flag Redundancies 6. User Flags 6.1 Format Of User Flags 6.2 Mail Oriented User Flags
The Fidonet Distribution Nodelist (FTS-5000) is a comma-delimited database, i.e. each node's entry is made up of fields, each of which has a specific purpose.
While this is a fine system for holding information that all nodes must have (e.g. node number, sysop name, etc.) it is not well suited for data that varies wildly from system to system. To accommodate such data, the flag fields are defined as self-describing and non-position dependent fields.
This document is a registry of all commonly used flags in Fidonet, and companion to FTS-5000 in describing the Distribution Nodelist.
2. Supersessions ----------------
This document supersedes and replaces FTS-0005, FSC-0009, FSC-0040, FSC-0062, FSC-0075 and FSC-0091.
3. Purpose ----------
As with FTS-5000, this document is intended for both developers and nodelist maintainers to avoid duplication and conflicts. Normal sysops would also do well to have at least cursory knowledge of the nodelist's capabilities so they may provide their Coordinators with all the pertinent detail of their systems.
This document should be considered a guide, and not the final word on what are and aren't valid flags. There will obviously be an unavoidable lag between the introduction of new flags and their inclusion in this document, as well as experimental flags that will come and go with no official documentation at all.
4. Syntax ---------
Most flags are simple tokens that each occupy a single field and by their presence or absence in the nodelist, indicate the presence or absence of a certain feature in the node.
A more recent style is to subdivide the flag field, usually with a colon (3Ah) to allow for variable data under a common flag. These are essentially named fields, consisting of the flag itself and its payload as one or more subfields.
Unless otherwise stated, flags are not position or order dependent, with the exception that User Flags must follow Normal Flags.
CM Node accepts mail 24 hours a day using all listed methods ICM Node accepts mail 24 hours a day using all listed TCP/IP methods, but not all of the other listed methods (such as PSTN/ISDN) and therefore cannot be CM. See FRL-1017. MO Node does not accept human callers LO Node accepts calls Only from Listed FidoNet addresses MN Compressed mail packets will not be processed automatically
* NOTE: maximum possible speed; actual maximum will vary depending on implementation.
5.3. Session Level Error-correction and Compression Flags ---------------------------------------------------------
The following flags define type of error correction and/or data compression available. A separate error correction flag should not be used when the error correction type can be determined by the modem flag. See section I for details.
Flag Meaning
MNP Microcom Networking Protocol error correction of type MNP1 to MNP4 V42 ITU-T V.42: LAP-M error correction with fallback to MNP 1-4 V42b ITU-T V.42bis: LAP-M error correction and compression with fallback to MNP 1-5
The following table shows the flags indicating various types of file/update requests supported:
+--------------------------------------------------+ | | Bark | WaZOO | | |---------------------|---------------------| | | File | Update | File | Update | | Flag | Requests | Requests | Requests | Requests | |------|----------|----------|----------|----------| | XA | Yes | Yes | Yes | Yes | | XB | Yes | Yes | Yes | No | | XC | Yes | No | Yes | Yes | | XP | Yes | Yes | No | No | | XR | Yes | No | Yes | No | | XW | No | No | Yes | No | | XX | No | No | Yes | Yes | | none | No | No | No | No | +--------------------------------------------------+
The following software is qualified to use the appropriate file request flag according to information provided by developers:
+-----------------------------------+ | Flag Software Package | |-----------------------------------| | XA Frontdoor 1.99b and lower | | Frontdoor 2.01 and higher | | Dutchie 2.90c | | Binkleyterm 2.1 and higher | | D'Bridge 1.2 and lower | | Melmail | | TIMS | | ifcico | | mbcico 0.60.0 and higher| | (via modem) | |-----------------------------------| | XB Binkleyterm 2.0 | | Dutchie 2.90b | |-----------------------------------| | XC Opus 1.1 | |-----------------------------------| | XP Seadog | |-----------------------------------| | XR Opus 1.03 | | Platinum Xpress | |-----------------------------------| | XW Fido 12N and higher | | Tabby | | TrapDoor No update processor| | binkd w/SRIF FREQ processor | |-----------------------------------| | XX Argus 2.00 and higher | | D'Bridge 1.30 and higher | | Frontdoor 1.99c/2.00 | | InterMail 2.01 | | McMail 1.00 | | T-Mail | | TrapDoor - Update Processor | | mbcico 0.60.0 and higher| | (via IP) | |-----------------------------------| | None QMM | +-----------------------------------+
5.5. Gateway Flag -----------------
The following flag defines gateways to other domains (networks).
Flag Meaning
Gx..x Gateway to domain 'x..x', where 'x..x` is a string of alphanumeric characters. Valid values for 'x..x' are assigned by the FidoNet International Coordinator or the Zone Coordinators Council. They will also adequately distribute a list of valid values.
5.6. Mail Period Flags ----------------------
The Mail Period Flags indicate compliance with another zone's ZMH. Since ZMH is mandatory within one's own zone, it is not indicated.
These flags have the form "#nn" or !nn where nn is the UTC hour the mail period begins, # indicates Bell 212A compatibility, and ! indicates incompatibility with Bell 212A. For example:
Flag Meaning
#02 Zone 2 mail hour (02:30 - 03:30 UTC) #08 Zone 4 mail hour (08:00 - 09:00 UTC) #09 Zone 1 mail hour (09:00 - 10:00 UTC) #17 Zone 3 mail hour (17:00 - 18:00 UTC)
The above listing of the ZMH for each individual zone is only given for your convenience. It was correct at the time of this writing, but could be changed at any time by following the procedures established in Fidonet policy. The FTSC has no role in determining the Mail Hour of any Zone. You'll find an up-to-date list in the comments at the end of the Fidonet Nodelist.
NOTE: When applicable, the mail period flags may be strung together with no intervening commas, e.g. "#02#09".
5.7. System Online Flags ------------------------
The flag Tyz is used by non-CM nodes online not only during ZMH, y is a letter indicating the start and z a letter indicating the end of the online period as defined below (times in UTC):
A 0:00, a 0:30, B 1:00, b 1:30, C 2:00, c 2:30, D 3:00, d 3:30, E 4:00, e 4:30, F 5:00, f 5:30, G 6:00, g 6:30, H 7:00, h 7:30, I 8:00, i 8:30, J 9:00, j 9:30, K 10:00, k 10:30, L 11:00, l 11:30, M 12:00, m 12:30, N 13:00, n 13:30, O 14:00, o 14:30, P 15:00, p 15:30, Q 16:00, q 16:30, R 17:00, r 17:30, S 18:00, s 18:30, T 19:00, t 19:30, U 20:00, u 20:30, V 21:00, v 21:30, W 22:00, w 22:30, X 23:00, x 23:30.
For example TuB shows an online period from 20:30 until 1:00 UTC.
Daylight saving time --------------------
If a node changes online times with respect to UTC when daylight saving time becomes effective (which would be the case with most part time nodes), then this is to be taken into account when assigning this flag. An online times flag assigned to a node should not be altered for the specific purpose of adjusting due to daylight saving time, since large difference files (NODEDIFF's) would result if every node was allowed to do this, e.g. a node used to be online from 2300 to 0800 in local time, which in winter is UTC, but in the summer it becomes BST (British Summer Time). This is one hour ahead of UTC, and the corresponding availability times of a node during the summer period were 2200 to 0700 UTC. Therefore its online times flag would have indicated availability between the hours of 2300 and 0700 UTC, the daily time period encompassing both times, so the flag would be TXH.
Nodelist Specification of minimal support required for this flag; flag any additional support to be arranged via agreement between users
V110L ITU-T V.110 19k2 async ('low'). NOTE: some implementations are limited to 9600bps. V110H ITU-T V.110 38k4 async ('high'). V120L ITU-T V.120 56k async, layer 2 framesize 259, window 7, modulo 8. V120H ITU-T V.120 64k async, layer 2 framesize 259, window 7, modulo 8. X75 ITU-T X.75 SLP (single link procedure) with 64kbit/s B channel; layer 2 max. framesize 2048, window 2, non-ext. mode (modulo 8); layer 3 transparent (no packet layer). ISDN Other configurations. Use only if none of the above fits.
NOTE: No flag implies another. Each capability MUST be specifically listed.
5.9. Internet Capabilities --------------------------
Basic Syntax ------------
Internet capability flags use the format:
<flag>[:<internet address>][:<port>]
Where <internet address> is: * a fully qualified domain name (FQDN), or * an IPv6 address encased in square brackets, or * an IPv4 address in dotted-quad format, or * an email address,
depending on the protocol, and <port> is the service port number.
<internet address> may be omitted if the address is available in another field (see below). <port> should be omitted if it is the default port for that particular service, and is not permitted for email addresses.
The mailer software is expected to be able to determine whether <internet address> is an IPv4 quad, an IPv6 encased address, a host name or email address by itself.
Advanced usage --------------
Several methods of listing Internet capability flags are widely used and subject to change at any time. Internet capable software should provide a suitable manual override mechanism to compensate for the volatility of the nodelist format, and be able to deal with prolonged connection failures (e.g. by automatically putting waiting mail on hold, and notifying the local sysop).
Shorthand flags ---------------
For brevity, a node that lists multiple Internet capability flags that require the same address may list the address only once, and specify only port numbers per flag if required.
Ideally, a node should use the flags specifically intended for this purpose, but that is not always the case. Be prepared to look for addresses under any flag of the same type.
Multihomed systems ------------------
Multihomed systems or systems that are otherwise reacheable by more than one address, may - instead of adding another A or AAAA record to the DNS zone of the host name - repeat the flag(s) carrying the address with another address.
This method is not to be used to signal that a system is IPV4 and IPv6 capable. Additional IPv6 capability should be advertised by adding an AAAA record to an already listed host name.
Alternate fields ----------------
If the address is not attached to any of the Internet capability flags, it may be present in another field (see FTS-5000).
Because of this, systems using Internet capability flags should avoid entering data in such fields that may be mistaken for Internet related information. For example, a node with an email flag should not use a system name that could be confused with an email address.
DNS Distributed Nodelist ------------------------
"Precompiled" IP connection information may also be obtained from one of the local or publicly available DNS Distributed Nodelist (DDN) services. This is documented in FTS-5004.
Indirect Delivery -----------------
Not all Internet tunneling methods require the originating node and the destination node to make a direct, realtime connection. Relays through the FTP or email servers of an ISP may serve as an example.
To avoid unusual delays, nodes using such 3rd party relays should check regularly for new mail -- daily for non-CM nodes, and hourly for CM nodes is recommended.
Where multiple protocols are available, the originating node should select the most direct method, and avoid protocols that may be using relays.
Standard Flags --------------
Default Flag port Description --------------------------
INA (none) This flag sets the default Internet address used for any non-email based flag that does not specify its own. This flag does not carry a port number. IP (none) Mostly used during the introduction of IP capable systems to the nodelist, is similar to the INA flag but may or may not specify an Internet address. Both usages are deprecated in favour of INA.
IBN 24554 Binkp (FTS-1026 - FTS-1029) IFC 60179 RAW ifcico (FTS-1024) IFT 21 FTP (RFC-0959); Note there is currently no widely accepted authentication scheme for FTP transfers by Fidonet mailers. ITN 23 Telnet connection using FTS-1 or any other protocol designed for classic POTS and modem. IVM 3141 Vmodem connection using FTS-1 or any other protocol designed for classic POTS and modem.
INO4 (none) Indicates that an otherwise IP capable node is unable to accept incoming connections over IPv4. (FRL-1038) This flag does not carry an address or port number.
Email Flags -----------
To use the flag for any Email method providing for return receipts (currently ITX and ISE) a node *must* have them enabled and send such receipts within 24 hours of receiving a file.
Flag Description --------------------------
IEM Indicates an unspecified mail tunnelling method (old usage, similar to IP), or sets the default email address for other flags (similar to INA)
ITX TransX encoding for email tunnelling with receipts enabled. IUC uuencoding of mail bundles IMI MIME encoding of mail bundles ISE SEAT protocol for Email tunnelling with receipts. enabled; should always be accompanied by IUC and/or IMI. > EVY Voyager-compatible > EMA Everything not defined by the aforementioned individual flags
The e-mail flags do not carry a port number.
Reliability -----------
It should be noted that only some of these Internet based methods (currently IBN, IFC, ITN, IVM, ITX and ISE) can give the sender a proof of receipt of a file by the addressee, like FTS-0001 does.
Other methods have no guarantee of reliability, so they shouldn't be used to transmit critical data.
Also, nodelist segment maintainers should take into account the presence of at least one of these reliable protocols when deciding on application for Fidonet membership by nodes without a dial-up connection.
5.10. Robot flags -----------------
PING ----
Specified as exactly "PING" with no arguments. Nodes flying this flag will adhere to the following functionality:
1) PING-function:
If a message destined to "PING" arrives at its final destination and this final destination flies the "PING"-flag, then the receiving node will bounce the message back to the original sender clearly quoting all the original via-lines.
If a message destined to "PING" arrives at its final destination but this final destination does _not_ fly the "PING"-flag then the message may be deleted from the inbound-queue without further follow-up.
2) TRACE-function:
If a message destined to "PING" arrives at a node which flies the PING-flag but is merely passing-through to another destination then the in-transit node will notify the sender of this occurrence and will forward the original mail unaltered towards its final destination.
WARNING: the sender's name (in either direction) must *NEVER* be "PING".
5.11. Flag Redundancies -----------------------
Only the smallest possible set of flags should be used in each entry.
Since different people might have different perception of modem flag redundancies, the FTSC decided to provide a standard table.
The relation "implies" means either that the first protocol requires all the others as a fallback or that to all practical purposes all modems which have been manufactured until today (and conceivably even future ones) implemented the other protocols anyway.
For example, the protocol V.32bis implies V.32 because it's required as a fallback; on the other hand, V.32Terbo implies V.32bis because practically all modems with V.32Terbo also had V.32bis to connect to existing modems, even though it wasn't required in the protocol specifications.
Please note also that: . the V90C and V90S flags are mutually exclusive. . the X2C and X2S flags are mutually exclusive. . no modem has at the same time the US Robotics proprietary protocols and the ZyXEL ones; so, use of any flag in the group HST, H14, H16, X2S and X2C is incompatible with any of the ZYX and Z19 flags, and vice versa. . all X? flags are mutually exclusive. . the CM flag is incompatible with any of the #??, !?? or T?? flags. . the CM flag implies ICM; ICM should not be used unless CM is impossible.
6. User flags -------------
It is impossible to document all user flags in use. The FTSC makes no attempt at it. This document lists those flags which got at least some kind of official sanction or were deemed of technical interest by FTSC.
6.1 Format Of User Flags ------------------------
U,x..x
A user-specified string, which may contain any alphanumeric character except blanks. This string may contain one to thirty-two characters of information that may be used to add user-defined data to a specific nodelist entry. The character "U" must not be repeated, eg, ",U,XXX,YYY,ZZZ" not ",U,XXX,U,YYY,UZZZ". The 32 character limitation is per userflag, not for the total of all userflags.
New implementations must place a comma after the initial "U" before the user flags. Some implementations will not place a separating comma between the "U" and the first user flag, but this practice is deprecated. Implementations should be prepared to read flags in this format, and must strip the "U" from the flag before analysis in this case.
Entries following the "U" flag must be of a technical or administrative nature. While experimentation of new software functions using this flag is encouraged, advertisement is strictly prohibited.
For applications other than those shown, or if you have questions concerning the use of this field, please contact your Regional or Zone Coordinator.
Developers should note that the distinction between "normal" flags and user flags is a non-technical, purely political one. It often happened that a user flag was "promoted" to regular status, and the reverse could conceivably happen. It is recommended that, while parsing nodelist entries, no distinction at all be done between the two categories of flags.
6.2. Mail Oriented User Flags -----------------------------
Flag Meaning
ZEC Zone EchoMail Coordinator. Not more than one entry in the zone segment may carry this flag and that entry must be the current Zone EchoMail Coordinator.
REC Regional EchoMail Coordinator. Not more than one entry in any region may carry this flag and that entry must be the current Regional EchoMail Coordinator.
NEC Network EchoMail coordinator. Not more than one entry in any net may carry this flag and that entry must be the current Network EchoMail Coordinator of that Net.
NC Network Coordinator. This flag is ONLY to be used by the Network Coordinator of a net which has split the duties of NC and Host and the NC does NOT occupy the Net/0 position in the nodelist.
SDS Software Distribution System
SMH Secure Mail Hub
RPK Regional Pointlist Keeper. This user-flag identifies the person who compiles the region-pointlist (only 1 entry per region allowed)
NPK Net Pointlist Keeper. This user-flag identifies the person who compiles the net-pointlist (only 1 entry per net allowed)
ENC This node accepts inbound encrypted mail and will route it like other mail
CDP This node will accept points auto-created by the CD-point software.
A. References -------------
[FTS-0005] "The distribution nodelist", Ben Baker, Rick Moore. February 1989.
[FSC-0009] "Nodelist Flag Changes Draft Document", Ray Gwinn, David Dodell. November 1987.
[FSC-0040] "Extended Modem Handling", Michael Shiels. February 1990.
[FSC-0062] "A Proposed Nodelist flag indicating Online Times of a Node", David J. Thomas. April 1996.
[FSC-0075] "ISDN capability flags in the Nodelist", Jan Ceuleers. October 1993
[FSC-0091] "ISDN nodelist flags", Arjen Lentz. October 1995.
[FRL-1036] "IPv6 numbers in the nodelist". March 2010
[Policy] "FidoNet Policy Document" v4.07 - June 9, 1989.
B. History ----------
Rev.1, 1999-06-27: Initial Release. Principal Author David Hallford
Rev.2, 2000-04-22: new draft by Gino Lucrezi; major changes: - reorganization of flags classification - rewrite for clarification of internet connection flags - note on difference between "regular" and "user" flags - description of flag redundancies new draft by Gino Lucrezi with input from others - removed Andreas Klein from authors - ENC flag - distinction of direct and indirect IP connectivity - requirement for return receipts with ITX and ISE - additional requirement for IP-nodes with CM flag - clarification on some flag redundancies new draft by Gino Lucrezi with input from others - corrected Z3MH and added note on changing of ZMHs
Rev.2, 2004-09-04: re-re-draft by FTSC. - Changed header style - Added Introduction and Purpose sections - Added Syntax section - Rewrite of Internet connectivity section - Removed IP flag conversions - Merged IP flags and default ports tables - Added ifcico to compatibility table - Fixed Txy flag status (user flag >normal flag) - Removed ISDN conversions and redundant 300 bps limit (specified in FTS-5000) - Removed 32 character flag limitation - Removed obsolete flag: V21 - Removed obsolete flag: V33 - Removed obsolete flag: MAX - Removed obsolete flag: K12 - Updated V?? flags - Added ICM flag - Added PING flag - Added flag redundancy table
Rev.3 2013-01-04 - There is no version 3. The above version 20040904 should have been labelled version 3, but due to a clerical error it was also labelled version 2. So there are two version 2's. Rather than attempting to correct the error, which would probably not have succeeded as it is next to impossible to recall a file that was hatched many years ago, it was decided to leave things as they are, skip version 3 and carry on with version 4.
Rev.4, 2013-03-10 - Updated the paragraph on DDN in section 5.9 to reflect that the DDN project is now documented in separate document FTS-5004. - Upgraded the description of the MN flag - Removed reference to port numbers for e-mail flags. - Added IPv6 where literal IP numbers are referenced. - Removed reference to Z5 and Z6. (#nn flags) - Added "binkd w/SRIF FREQ processor" to list of programmes qualifying for XW freq flag. - Dropped NSMH, RSMH, ZSMH and ISMB. Obsolete. - Clarified meaning of ITN and IVM flag. - Various small changes in wording and correc- ting spelling errors. - Added repeating of flags in case of systems having multiple adresses.
> Rev.5, 2014-07-01 - Reformatted to comply with FTA-1002.003 - Added INO4 flag - Corrected some spelling errors
> Rev.6, 2017-03-27 - Added EVY and EMA flags > - History: Changed second occurance of history > Rev 4 to Rev 5
