X.400 addresses are ugly

Contrast the following two strings: (This, btw, is an old address of mine; don't use it)

There are several apparent differences:

There are also differences that aren't apparent on the surface, but become clear when you investigate underlying technology: The use of the ADMD field brings to mind what Rob Frieden writes in his "International Telecommunications Handbook" (ISBN 0-89006-568-3):
The greatest degree of negotiating clout will lie with users who generate large traffic volumes and can migrate to other suppliers, or who can install their own equipment
The ADMD name is a bar to migrating to another supplier; the routing habit is a bar to "installing your own equipment" - that is, PRMDs cross-connecting to other PRMDs or ADMDs. In some countries, it's even illegal....

There are also some important commonalities:

You might be convinced of the superiority of one scheme over the other already, but read on....

Attribute-based addressing

X.400 was designed with attributed addresses. The complete set of attributes is rather large; this table comes from RFC 1685, which in turn copied it from F.401 annex F (this was added to the standard in early 1993; before this, there was no standardized way to write down an X.400 address, which led to some confusion):

    Attribute Type                         Abbreviation      Label
                                           (where necessary)

    Given Name                             Given name        G
    Initial                                Initials          I
    Surname                                Surname           S
    Generation Qualifier                   Generation        Q
    Common Name                            Common Name       CN
    Organization                           Organization      O
    Organizational Unit 1                  Org.Unit.1        OU1
    Organizational Unit 2                  Org.Unit.2        OU2
    Organizational Unit 3                  Org.Unit.3        OU3
    Organizational Unit 4                  Org.Unit.4        OU4
    Private Management Domain Name         PRMD              P
    Administration Management Domain Name  ADMD              A
    Country                                Country           C
    Physical Delivery Personal Name        PD-person         PD-PN

    Extension of Postal O/R Address
    Components                             PD-ext.address    PD-EA
    Extension of Physical Delivery Address
    Components                             PD-ext.delivery   PD-ED
    Physical Delivery Office Number        PD-office number  PD-OFN
    Physical Delivery Office Name          PD-office         PD-OF
    Physical Delivery Organization Name    PD-organization   PD-O
    Street Address                         PD-street         PD-S
    Unformatted Postal Address             PD-address        PD-A1
    (there are individual labels for                         PD-A3
    each line of the address)                                PD-A4
    Unique Postal Name                     PD-unique         PD-U
    Local Postal Attributes                PD-local          PD-L
    Postal Restante Address                PD-restante       PD-R
    Post Office Box Address                PD-box            PD-B
    Postal Code                            PD-code           PD-PC
    Physical Delivery Service Name         PD-service        PD-SN
    Physical Delivery Country Name         PD-country        PD-C

    X.121 Network Address                  X.121             X.121
    E.163/E.164 Network Address            ISDN              ISDN
    PSAP Network Address                   PSAP              PSAP
    User Agent Numeric ID                  N-ID              N-ID
    Terminal Identifier                    T-ID              T-ID
    Terminal Type                          T-TY              T-TY
    Domain Defined Attribute               DDA:

    where the notation  identifies the type of domain defined

Most of these aren't used very much; those with PD- in front of them are used with X.400 networks that support delivery of mail by printing it onto paper and sending it to the postal service, and the only one I've seen used out of the network crowd is the X.121, which some ADMDs use to address fax machines through the telephone network.

[soap....] I regard attribute-based addressing as a mistake.
This stems from the fact that attribte labels tend to make people believe that the named entity should have some property associated with the label; for instance, they expect something to be an organization just because it is named in the "organization" field, and something "should be" a person just because it has a "surname" field.

They also expect address hierarchies to conform to organizational charts, thinking that OU1=trondheim; OU2=sales means that there is a Trondheim office controlling the Trondheim sales department. (Trondheim is a city), or expect an user to work for an organization just because he uses its O field, while he is in fact a customer of their service. [....soap]

Other problems include the use of "country": SITA, the airline industry network, has unilaterally started to use "C=WW" for "world wide", because several of its customers refused to be locked into a statement about which country they were located in, and the ISODE Consortium, with offices in the UK and USA, uses "C=FI" because their service provider happens to be operating out of Finland.

X.400 extensions to the addressing format

X.400 (88) brought fresh life into addressing.

It added an extension mechanism, allowed most attributes to be written using the Teletex charset (Japanese characters, and most accents, but NOT greek, Arabic or Sanskrit), and then added the proviso that you had to make all the mailboxes addressable using the older PrintableString attributes, because you couldn't expect everyone in the world to be fluent Kanji typists.

It also added the "Common Name", "because it seems so silly to talk about the surname of a process or mailing list", adding further to the confusion, and not helping ease of mapping at all.

There have been moves afoot to add the possibility of putting Internet-style addresses into X.400 addresses as a new attribute, making life easier for the Internet gateways, but rather harder for those whose UAs haven't even found out what a Common Name is yet.

Another interesting twist is the "special ADMD values", SPACE for indicating "You may route on the C,PRMD tuple, and if you are connected to any ADMD in the country, you can expect it to be delivered", which works with at least some UK ADMDs, and the zero ("0") for indicating that you are in a PRMD that is connected to no ADMD, so if you don't have a route directly to it, you can drop the message immediately.
The latter one hasn't exactly been a raging success...

Weird examples of Internet adressing

Well..all isn't well with the "simple" Internet address format either. Look at some of these examples (user names ONLY changed to protect the guilty):
  (current leader in category "abusive domain name". Apparently worked!)
  (current leader in category "abusive user naming"; it couldn't be
  replied to either)
  (rabid rewriters may think they know what a percent sign is for)
  (produced by Banyan Vines gateways; I don't have a working example)
  (most cryptic address format in widespread use)
Common to most of these are: The native Internet address style tolerates these abuses. I don't think it condones or promotes them.
Last modified: Thu Jun 20 09:30:05 1996