Protocol-A.texi

\input texinfo                         @c -*-texinfo-*-
@c
@c FIXME: Explain how the garb works with nice and keep-commented
@c FIXME: Make all types clickable in HTML (and info?)
@c FIXME: Move predefined aux-items to separate chapter
@c FIXME: Move misc-infos to chapter?
@c FIXME: Check for too much text before @menu.
@c FIXME: error-reply defined twice (conflicting).
@c FIXME: add link to Name Expansion from relevant reqs.
@c FIXME: Name Expansion collate table info is outdated.
@c FIXME: sentence-end-double-space!
@c
@c $Id: Protocol-A.texi,v 1.132 2001/05/01 17:11:24 ceder Exp $
@c %**start of header
@setfilename protocol-a.info
@settitle LysKOM Protocol A
@setchapternewpage odd
@c @afourpaper

@set PROTOEDITION 10.4
@set PROTOVER 10
@set VERSION 1.0.4



@c
@c Define a few strings that contains characters from ISO Latin-1.
@c

@iftex

@set IAM Inl@"a{}gg @}t mig
@set Pell P@"ar Emanuelsson
@set Kent Kent Eng@-str@"om@penalty-10000
@set presconf 27HPresentation (av nya) m@"oten

@end iftex
@ifnottex

@set IAM Inlägg @}t mig
@set Pell Pär Emanuelsson
@set Kent Kent Engström
@set presconf 27HPresentation (av nya) möten

@end ifnottex



@c
@c Index setup
@c

@c Index for asynchronous messages.
@defcodeindex am

@c Merge all indices.
@syncodeindex am fn
@syncodeindex tp fn



@c
@c Special markup for Protocol-A.texi
@c

@c @req{login} is used for protocol requests.

@macro req {n}
@code{\n\}
@end macro

@c @reqlink{login} is used for protocol requests, that shuld be linked.

@ifhtml
@macro reqlink {n}
@code{@ref{\n\}}
@end macro
@end ifhtml

@ifnothtml
@macro reqlink {n}
@code{\n\} (@pxref{\n\})
@end macro
@end ifnothtml

@c @reqdlink{login}...@linkhere{} is used for protocol requests, that
@c shuld be linked, where the link should occur a few words after the
@c request itself.

@ifhtml

@c HTML version: make the word a link.
@macro reqdlink {n}
@code{@ref{\n\}}@c
@unmacro linkhere
@macro linkhere
@end macro
@end macro

@end ifhtml

@ifnothtml
@ifnottex

@c Info version: create linkhere as a macro that contains a reference.

@macro reqdlink {n}
@code{\n\}@c
@unmacro linkhere
@macro linkhere
(@pxref{\n\})
@end macro
@end macro
@end ifnottex

@iftex

@c TeX version: this produces output similar to the Info version.

@tex
    \gdef\reqdlink#1{%
        \code{#1}%
        \gdef\linkhere{ (\pxref{#1})}%
    }
@end tex
@end iftex
@end ifnothtml

@c @aux{mx-allow-filter} is used for aux-item names.
@macro aux {n}
@code{\n\}
@end macro

@c @async{async-login} is used for async names.
@macro async {n}
@code{\n\}
@end macro

@c @asynclink{async-login} is used for async names, that shuld be linked.

@ifhtml
@macro asynclink {n}
@code{@ref{\n\}}
@end macro
@end ifhtml

@ifnothtml
@macro asynclink {n}
@code{\n\} (@pxref{\n\})
@end macro
@end ifnothtml

@c @asyncdlink{async-login}...@linkhere{} is used for async messages,
@c that shuld be linked, where the link should occur a few words after
@c the async name itself.

@ifhtml

@c HTML version: make the word a link.
@macro asyncdlink {n}
@code{@ref{\n\}}@c
@unmacro linkhere
@macro linkhere
@end macro
@end macro

@end ifhtml

@ifnothtml
@ifnottex

@c Info version: create linkhere as a macro that contains a reference.

@macro asyncdlink {n}
@code{\n\}@c
@unmacro linkhere
@macro linkhere
(@pxref{\n\})
@end macro
@end macro
@end ifnottex

@iftex

@c TeX version: this produces output similar to the Info version.

@tex
    \gdef\asyncdlink#1{%
        \code{#1}%
        \gdef\linkhere{ (\pxref{#1})}%
    }
@end tex
@end iftex
@end ifnothtml

@c @type{Conference} is used for LysKOM types.
@macro type {n}
@code{\n\}
@end macro

@c @lt{Conference} is used for linked types.  The link is only present
@c when it is unobtrusive.  It should only be used inside
@c @example...@end example.

@ifhtml
@macro lt {n}
@ref{\n\}@c
@end macro
@end ifhtml

@ifnothtml
@macro lt {n}
\n\@c
@end macro
@end ifnothtml

@c @priv{wheel} is used for privilege bits.
@macro priv {n}
@code{\n\}
@end macro

@c @conftype{rd-prot} is used for conference type bits.
@macro conftype {n}
@code{\n\}
@end macro

@c @misc{bcc-recpt} is used for misc-info names.
@macro misc {n}
@code{\n\}
@end macro

@c @rarg{passwd} is used to reference arguments of requests.  This is
@c *only* used in the nodes that defines the requests.
@macro rarg {n}
@code{\n\}
@end macro

@c @aarg{text-no} is used to reference arguments of asynchronous
@c messages.  This is *only* used in the nodes that defines the
@c relevant asynchronous message.
@macro aarg {n}
@code{\n\}
@end macro

@c @errorcode{no-such-text} is used to mark error codes.
@macro errorcode {n}
@code{\n\}
@end macro

@c @field{ident-user} is used to mark fields of struct types.
@macro field {n}
@code{\n\}
@end macro

@c @reqexample is used immediately before Protocol-A example
@c fragments.
@macro reqexample
@need 2000
@i{Example:}
@end macro

@c %**end of header

@ifinfo
This is the LysKOM Protocol A specification, edition
@value{PROTOEDITION}.  It specifies version @value{PROTOVER} of the
protocol.  It corresponds to version @value{VERSION} of lyskomd.

Copyright @copyright{} 1995-2000 Lysator ACS.

Permission is granted to make and distribute verbatim copies of this
specification provided the copyright notice and this permission notice
are preserved on all copies.

@ignore
Permission is granted to process this file through TeX
and print the results, provided the printed document
carries a copying permission notice identical to this
one except for the removal of this paragraph (this
paragraph not being relevant to the printed manual).
@end ignore

Modified versions of this document may be redistributed with the added
condition that all modifications not cleared with the LysKOM development group
are clearly marked and that the entire modified work be redistributed under the
same conditions as the original.

Permission is granted to copy and distribute translations of this manual into
another language under the same conditions as for modified versions.
@end ifinfo

@c FIXME: What does this do?
@iftex
@parindent 0pt
@font@tensltt=cmsltt10
@tex
\global\def\rett#1{{\let\t\sltt\tt #1}}
\global\def\sltt#1{{\fam\ttfam\tensltt\let\t\rett #1}}
\global\let\t\sltt
@end tex
@end iftex

@titlepage
@title{LysKOM Protocol A}
@subtitle{Protocol version @value{PROTOVER}}
@subtitle{Edition @value{PROTOEDITION}}
@subtitle{(lyskomd @value{VERSION})}
@author by the LysKOM Developers

@page
@vskip 0pt plus 1filll
Copyright @copyright{} 1995-2000 Lysator ACS

Permission is granted to make and distribute verbatim copies of this document
provided the copyright notice and this permission notice are preserved on all
copies.

Modified versions of this document may be redistributed with the added
condition that all modifications not cleared with the LysKOM development group
are clearly marked and that the entire modified work be redistributed under the
same conditions as the original.

Permission is granted to copy and distribute translations of this manual into
another language under the same conditions as for modified versions.

@end titlepage
@ifnothtml
@contents
@end ifnothtml

@dircategory LysKOM
@direntry
* Protocol A: (protocol-a).             The LysKOM Protocol A specification.
@end direntry

@ifhtml
@html
<a href="http://www.lysator.liu.se/" ><img
src="http://www.lysator.liu.se/icons/lyslogo.gif" alt="Lysator"
width=40 border=0 height=40 align=left ></a>

<a href="http://www.lysator.liu.se/lyskom/" ><img
src="http://www.lysator.liu.se/icons/lyskom.gif" alt="LysKOM" width=40
border=0 height=40 align=left ></a>
<br clear=all>
@end html
@end ifhtml
@ifnottex
@node Top
@top LysKOM Protocol A

This document specifies version @value{PROTOVER} of LysKOM Protocol A.
This is edition @value{PROTOEDITION} of the specification.  It
corresponds to version @value{VERSION} of lyskomd.

The most up-to-date version if this document can always be found at 
@uref{http://www.lysator.liu.se/lyskom/protocol/}.
@end ifnottex

@menu
* Overview::                    
* Introduction::                
* Data Types::                  
* Protocol Requests::           
* Asynchronous Messages::       
* Error Codes::                 
* Name Expansion::              
* LysKOM Content Types::        
* The User Area::               
* Writing Clients::             
* Importing and Exporting E-Mail::  
* Future changes::              
* Protocol Version History::    
* Document Edition History::    
* Index::                       
@end menu

@node Overview
@chapter Overview

@iftex
This document specifies version @value{PROTOVER} of LysKOM Protocol A.
This is edition @value{PROTOEDITION} of the specification.  It
corresponds to version @value{VERSION} of lyskomd.

The most up-to-date version if this document can always be found on
the web at @uref{http://www.lysator.liu.se/lyskom/protocol/}.
@end iftex

LysKOM is a conferencing system@footnote{Or in modern terms, enabling
technology for Computer-Supported Cooperative Work (CSCW).}. Similar
systems were QZ-KOM and PortaCOM@footnote{Also known as ``PottaKOM'' and
``BortaKOM.''}. The LysKOM system is copyrighted by Lysator Academic
Computing Society and distributed under conditions of the GNU Public
License. LysKOM and its documentation is provided ``as is'' without
warranty of any kind.

Anything described here as ``unspecified'' is liable to change in
future protocol versions.

This specification is the work of several people. The main contributors have
been
Per Cederqvist @email{ceder@@lysator.liu.se}, 
David Byers @email{byers@@lysator.liu.se},
@value{Pell} @email{pell@@lysator.liu.se},
Thomas Bellman @email{bellman@@lysator.liu.se}, 
Lars Aronsson @email{aronsson@@lysator.liu.se},
Linus Tolke @email{linus@@lysator.liu.se} and
@value{Kent} @email{kent@@lysator.liu.se}.

The LysKOM developers can be reached by email to
@email{lyskom@@lysator.liu.se}.

@menu
* Notation::                    
@end menu

@node Notation
@section Notation

This specification uses a BNF-like grammar to describe the protocol and
its data elements.

Data fields have been given names that start with a lower-case letter.

Fundamental data types have names in all-caps (such as @type{INT32} and
@type{ARRAY}).

Derived data types have names that start with an upper-case letter. (If
the type contains more than one word, all words start with an upper-case
letter, like this: @type{Text-Stat}.)  The operator @code{::=} defines
the name to its left.

Comments start with @code{!} (exclamation mark) and alternatives are
separated by a @code{|} (vertical bar.) A @code{;} (semicolon)
terminates statements in the grammar. In some specifications there are
literal strings. There is to be no whitespace before or after literal
strings unless there is whitespace in the literal itself.


@node Introduction
@chapter Introduction

This chapter introduces the concepts used in LysKOM, such as articles,
conferences and sessions. 

@menu
* Articles::                    
* Conferences::                 
* The Misc-Info List::          
* The Aux-Item List::           
* Security::                    
* Membership and Reading::      
* Client-Server Dialog::        
@end menu


@node Articles
@section Articles

An article is represented as a value of the type @type{Text-Stat} and a
string containing the article contents. An article will usually have one
or more recipients and may be a comment or footnote to other articles.
Each article is kept in the database until it is older than the
@field{nice} value of each of its recipients and it is not marked by any
user.

Currently there is an array of @type{Misc-Info} included in the
@type{Text-Stat}. This array contains information about recipients,
senders, comments and footnotes.

Every article has at least one number, the global article number. Global
numbers are assigned in ascending order to new articles, and are never
reused. If an article has recipients it will also have a local number
for each recipient. Local numbers are used in some data structures to
provide more compact storage and to provide an ordering of articles for
a particular recipient. Local numbers are assigned in ascending order
and are never reused for a particular recipient, though different
recipients will have articles with the same local numbers.

Occasionally it is necessary to map between local and global numbers.
The server call @reqlink{local-to-global} does this.



@node Conferences
@section Conferences

Conferences hold articles. They are represented in the protocol as a
data type called @type{Conference}. Each conference has a
@dfn{creator}, the person who created the conference, and a
@dfn{supervisor}, a conference whose members can modify the conference.
If the supervisor is a person, the members of that person's mailbox
are supervisors, which in most cases is only that person. We have also
introduced a type called @type{UConference} (pronounced micro-conf-stat)
which holds a subset of the information contained in the full
@type{Conference} type. Use the @type{UConference} type whenever
possible since it places a much smaller load on the LysKOM server.

Each conference has a type, which is essentially a collection of
boolean flags. Currently the flags @conftype{rd-prot},
@conftype{letterbox}, @conftype{secret}, @conftype{original},
@conftype{allow-anonymous} and @conftype{forbid-secret} are defined.

@table @conftype
@item rd-prot
The conference is protected from reading by non-members. Persons become
members by having one of the existing members or supervisors add him or
her to the conference. This restriction is enforced by the server.
@item original
Conferences of this type are intended for original articles only.
Comments are to be redirected to the super-conference instead. This
restriction is currently not enforced by the server; clients must
implement this functionality.
@item letterbox
Conferences of this type are connected to persons. Letters to a person
are sent to the mailbox and the name of the mailbox is synchronized
with the person name. It is currently not possible to explicitly set or
clear this flag on a conference.
@item secret
Conferences of this type are secret. The server will not divulge any
information about the existence of the conference to persons who are not
members or supervisors of the conference. If a mailbox is made secret,
that person cannot log in using the person name, but must specify a
person number instead.
@item allow-anonymous
Conferences of this type accept anonymous articles. Other conferences
will reject anonymous articles.
@item forbid-secret
Conferences of this type do not allow secret members. If a conference is 
changed to this type, preexisting secret members remain secret.
@end table



@menu
* Persons and Sessions::        
@end menu

@node Persons and Sessions
@subsection Persons and Sessions

Persons are represented in the protocol by values of the type
@type{Person}. Associated with persons are statistics, a set of personal
flags and a set of privileges (@pxref{Security}). Persons are also
associated with a conference that has the same number as the person and
the @conftype{letterbox} bit set.

Connections to the server are represented as values of the type
@type{Static-Session-Info}, @type{Session-Info-Ident} or
@type{Session-Info}. Sessions have session number that are unique for
each session in the lifetime of the server execution. A single user can
have several sessions running at once. The session is not released until
the network connection is closed; a user can log in and out repeatedly
in a single session.


@node The Misc-Info List
@section The Misc-Info List

The @type{Misc-Info} list contains tagged data. The fields are sent in
groups pertaining to a particular type of information: information about
recipient; carbon copy recipient; blank carbon copy recipient;
comment to; footnote to; comment in
and footnote in. The information groups may be sent in any order and
there may be any number of groups. Within each group the elements are
always sent in the order listed below.

@subsection Recipient

@table @misc
@item recpt
Starts a recipient group. It contains the conference number of a
recipient of the article.
@item loc-no
Always present within a recipient group. It contains the local text
number of the article in the conference specified by the preceding
@misc{recpt} field.
@item rec-time
If the recipient is a person, this element is added by the server when
the recipient marks the article as read. It contains the time when the
text was read.
@item sent-by
Present when the recipient was added by a person other than the author
(after the article was created.) It contains the person number of the
person who added the recipient.
@item sent-at
Present when the recipient was added after the article was created. It
contains the time when the recipient was added.
@end table


@subsection Carbon Copy (CC) Recipient

The carbon-copy recipient group is identical to the recipient group
above. The difference is how new comments to an article with a recipient
or carbon-copy recipient are treated. A comment to an article is sent to
all recipients, but not to carbon-copy recipients of the original
article. This difference is enforced by the clients.

@table @misc
@item cc-recpt
Starts a carbon-copy recipient group. It contains the conference number
of a carbon-copy recipient of the article.
@item loc-no
Always present in a CC recipient group. It contains the local text
number of the article in the conference specified by the most recent
@misc{cc-recpt} field.
@item rec-time
Present after the CC recipient has read the article. It contains the
time when the article was read. Since only persons can read articles
this will only be seen if the CC recipient is a person.
@item sent-by
Present when a CC recipient was added by a person other than the author
after the article had been created. It contains the person number of the
person who added the CC recipient.
@item sent-at
Present when a CC recipient was added after the article had been
created. It is the time when the CC recipient was added.
@end table


@subsection Blank Carbon Copy (BCC) Recipient

The blank carbon-copy recipient group is identical to the carbon-copy
recipient group above. The difference is the visibility of the
information. A carbon-copy recipient group is visible to anyone that is
allowed to fetch both the text status of the involved text and the
conference status of the involved conference.  (That is, as long as the
conference isn't secret everybody is allowed to see the carbon-copy
recipient group.)

A BCC recipient group is basically only visible to members and
supervisors of the recipient.  Persons that have the right to become a
member of the recipient can also see it, as can the author of the text
(unless the recipient is secret to him).  This is enforced by the
server.

This type of group was introduced in protocol version 10.  When
old-style calls such as @reqlink{get-text-stat-old}
are used this will be converted to a CC recipient group by the server
for the benefit of clients that don't understand this group.

@table @misc
@item bcc-recpt
Starts a blank carbon-copy recipient group. It contains the conference
number of a blank carbon-copy recipient of the article.
@item loc-no
Always present in a BCC recipient group. It contains the local text
number of the article in the conference specified by the most recent
@misc{bcc-recpt} field.
@item rec-time
Present after the BCC recipient has read the article. It contains the
time when the article was read. Since only persons can read articles
this will only be seen if the BCC recipient is a person.
@item sent-by
Present when a BCC recipient was added by a person other than the author
after the article had been created. It contains the person number of the
person who added the BCC recipient.
@item sent-at
Present when a BCC recipient was added after the article had been
created. It is the time when the BCC recipient was added.
@end table


@subsection Comment To

@table @misc
@item comm-to
Always present when the article is a comment to another article.
@item sent-by
Present when the article was added as a comment by a person other than
the author, after the article had been created. It contains the person
number of the person who added the article as a comment.
@item sent-at
Present when the article was added as a comment after the article had
been created. It contains the time when it was added as a comment.
@end table


@subsection Footnote To

@table @misc
@item footn-to
Always present when the article is a footnote to another article.
@item sent-at
Present when the article was added as a footnote after the article had
been created. It contains the time when it was added as a footnote.
@end table


@subsection Comment in

@table @misc
@item comm-in
Present when there are comments to this article. It contains the article
number which is a comment to this article.
@end table


@subsection Footnote in

@table @misc
@item footn-in
Present when there are footnotes to this article. It contains the
article number which is a footnote to this article.
@end table


@node The Aux-Item List
@section The Aux-Item List

The aux-item list is used as a generic extension mechanism in the LysKOM
server and in protocol A. 

@menu
* About Aux-Items::             
* Predefined Aux-Item Types::   
* Client-Specific Aux-Item Types::  
* Experimental Aux-Item Types::  
* Defining New Aux-Item Types::  
@end menu

@node About Aux-Items
@subsection About Aux-Items

Aux-items were introduced in protocol version 10 as a mechanism for
extending the conference, text and server information structures without
changing the protocol. Persons were excluded since nobody could figure
out a case where setting an aux-item on the mailbox wasn't as good as
setting it on the person (another reason was that I was fed up writing
aux-item code by the time they were working on texts and conferences.)

The exact structure of an aux item is specified elsewhere
(@pxref{LysKOM Data Types}). The important fields here are the
@field{aux-no}, @field{tag} and @field{data} fields.

The @field{aux-no} field is used to identify an item. The
@field{aux-no} together with a text or conference number uniquely
identifies a particular aux item.  Items are numbered from one and up
within each item list. Once assigned, the @field{aux-no} for an item
is never changed. New items are guaranteed to be assigned numbers that
have never been used before within a particular list.

The @field{tag} field identifies the type of aux item. It is used by
the server and by clients to figure out how to interpret the data
field, and by the server to decide if the item needs special
treatment.

The @field{data} field is a simple string. The meaning of the string
is determined by the @field{tag} field, but since it is a string,
clients that have no understanding of the contents can successfully
parse the item anyway (in contrast to items in the misc-info list.)



@node Predefined Aux-Item Types
@subsection Predefined Aux-Item Types

Predefined Aux-Item types are part of Protocol A, and clients should
support all of them. As with other parts of the protocol, changes to
these definitions will be made backwards-compatible, if possible.

Creation and deletion of items with a predefined type can cause
arbitrarily complex and wonderous behavior in the server. Furthermore,
the server may place constraints on the items with regard to content,
flags, who can create them, to what objects they can be attached and
so forth. The server may also silently enforce specific values for any
field of an item, regardless of what the client requests.

All items with tags in the range 1-9999 and 30000 and up are considered
predefined. If a client attempts to create an item with a tag in this
range, but the server has no idea what that tag means, the server will
return an error (illegal-aux-item.)

Some of the aux-items below (mostly the ones that begin with "mx-") are
used by mail importers. For information about supplementary aux-items
introduced by @command{komimportmail}, see @ref{komimportmail Aux-Item Types}.

@table @samp
@item content-type [1] (text)
Specifies the content type of a text. Data is a valid MIME type or one
of the special LysKOM types (@pxref{LysKOM Content Types}).

This item may only be set by the author of a text. The inherit, secret
and hide-owner bits are cleared. Only one content-type item can be
created per creator.


@item fast-reply [2] (text)
Data is a string that constitutes a brief comment to the text. This
comment should be displayed immediately after the text body. 

An item of this type will never be inherited, can always be deleted, is
never anonymous and is never secret.


@item cross-reference [3] (text, conference, letterbox)
Data is a cross-reference to something else. The contents consist of a
letter, a number, and optionally a space and a descriptive text. The
letter must be one
of T, C or P. T specifies that the cross-reference points to a text; C
that it points to a conference; and P that it points to a person. The
number is the id of the target of the cross reference. The descriptive
text is simly that, a text that describes the cross-reference. For
example, "T15 Check this out!" is a cross reference to text 15 with a
description that reads "Check this out!", and "T17" is a cross reference
without a description.

The inherit bit is automatically cleared and the item can always be
deleted. 


@item no-comments [4] (text)
When this item is set, the author requests that nobody comments the
text. This is advisory only; it is still possible to write comments, but
clients should advise the user that this is contrary to the author's
wishes. Data should be empty.

This item may only be set by the author. The secret, hide-creator and
inherit bits are automatically cleared.


@item personal-comment [5] (text)
When this item is set, the author requests only personal comments. This
is advisory only; it is still possible to create regular comments, but
clients should advise the user that the author prefers a personal
comment. Data should be empty.

This item may only be set by the author. The secret, hide-creator and
inherit bits are automatically cleared.


@item request-confirmation [6] (text)
The author requests that everyone who reads the text confirms having
done so by creating read-confirmation items on the text. Clients should
ask users if they wish to confirm having read the text when it is
displayed. Data should be empty.

The hide-creator, secret and inherit bits are automatically cleared.


@item read-confirm [7] (text)
This item can be taken as confirmation that the item creator has read
the text to which the item is attached. Clients should never ever create
this item without an explicit confirmation from the user that the text
has indeed been read.

The hide-creator, secret and inherit bits are automatically cleared.
Once created an item of this type cannot be deleted.


@item redirect [8] (conference, letterbox)

This item indicates that texts should not be sent to the conference,
but be directed to some other target instead. Clients should notify
users that attempt to send texts to the conference of the redirect and
offer to send the text to the target of the redirect instead. A typical
use of this item would be a user that does not read LysKOM very often
and would like to advise other users to send e-mail instead.

Data is PROTOCOL:ADDRESS where PROTOCOL is either "E-mail" or "LysKOM",
and ADDRESS is either an e-mail address or a LysKOM conference. 
Hopefully we'll be able to replace this with a forwarding mechanism
later.

This item can only be set by the conference supervisor or in the case of
a mailbox, the person attached to the mailbox. The hide-creator and
secret bits are cleared automatically. Only one redirect can be
specified.


@item x-face [9] (conference, letterbox, server)

Data is the face of the person in compface format. Cool, innit?

This item can only be set by the conference supervisor or in the case of
a mailbox, the person attached to the mailbox. The hide-creator and
secret bits are cleared automatically. 


@item alternate-name [10] (text, conference, letterbox)

Data is a string that the client may use as an alternate to the name of
a conference or the subject of a text. Note that the server does not
match against this name when performing name lookups. Clients should
only display alternate names created by the user currently logged on.

The inherit flag is automatically cleared.


@item pgp-signature [11] (text)

Data is a PGP signature of the text. The signature should be the
equivalent of what "pgp -sba" in PGP 2.6.2 generates.

The secret, hide-creator and inherit bits are automatically cleared.
Signatures cannot be deleted once they have been created.


@item pgp-public-key [12] (letterbox)

Data is the public key of the person. It is desirable that the public
key contains a userid of the format "LysKOM <p@var{n}@@@var{server}>+",
where @var{n} is the number of the person in the LysKOM server specified
in @var{server}. This rule is currently not enforced.

This item can only be set by the person himself. The hide-creator,
secret and inherit bits are automatically cleared.


@item e-mail-address [13] (conference, letterbox, server)

Data is an RFC 822-style email address. When set on a mailbox, it
should be the email address of the person. If the person has multiple
email addresses he may set serveral e-mail-address aux-items.

The meaning of this aux-item when set on a conference that isn't a
mailbox is vague. For a conference that is used as to import a mailing
list this should be the email address of the list. For other conferences 
we haven't really defined a sensible use.

When this aux-item is set on the server it shold contain the email
address of the administrator (or administrators.)

This aux-item can only be set by the supervisor of a conference or the
server administrator. The creator cannot be hidden.


@item faq-text [14] (conference, server)

Data is a decimal text number, which is a FAQ for the conference (or
server). Creating an item of this type automatically causes creation of
a faq-for-conf item.

This item can only be set by the supervisor or server administrator. The 
hide-creator, secret, and inherit bits are automatically cleared.


@item creating-software [15] (text)

Data is the name and version number of the client that created the
text.  This aux-item can only be set by the author of the text.  Once
set, it cannot be removed or changed.  A typical value would be
@samp{elisp-client 0.47.3}.  Setting the creating-software aux-item is
optional.

The data should be the client name, a space, and the client version used
in the @reqlink{set-client-version} call.  The server may enforce this
restriction.

@item mx-author [16] (text)

Data is a string containing the name of the author of an imported
e-mail, extracted from the @code{From} header.  This aux-item may be
missing, if the mail address in the @code{From} header consists of just
the @code{addr-spec} (see the next aux-item).

Clients should display this instead of the actual author of the text
(which will be an importer ID) even if an mx-from aux-item is not present.

Sample contents: @code{Joe Q. Public} which may come from a @code{From}
header containing @code{"Joe Q. Public" <john.q.public@@example.com>}.

@item mx-from [17] (text)

Data is the proper e-mail address (called @code{addr-spec} in the mail
standards) extracted from the @code{From} header of an imported
e-mail. 

Clients should display this address together with the @aux{mx-author},
preferably inside angles. If @aux{mx-author} is not present, this address
should be shown anyway. It can also be used by clients to construct an
address for personal (e-mail) replies to an imported message.

Sample contents: @code{john.q.public@@example.com} which may come from a
@code{From} header containing @code{john.q.public@@example.com} or
something like @code{"Joe Q. Public" <john.q.public@@example.com>}.

@item mx-reply-to [18] (text)

Data is the proper e-mail address (called @code{addr-spec} in the mail
standards) extracted from the @code{Reply-To} header of an imported
e-mail. Clients should use this for constructing replies to imported
messages.

@item mx-to [19] (text)

Data is a single e-mail address from an email @code{To} header.
Multiple @aux{mx-to} items may be present when multiple recipients are
specified in the header. Clients should display these items along
with the normal LysKOM recipient headers.

Sample contents: Both @code{john.q.public@@example.com} and
@code{"Joe Q. Public" <john.q.public@@example.com>} are valid.

@item mx-cc [20] (text)

Same as @aux{mx-to}, but applies to the @code{CC} header rather than
the @code{To} header.

@item mx-date [21] (text)

Data is the date and time from the @code{Date} header of an imported
email. Its format is "YYYY-MM-DD hh:mm:ss TZ". YYYY is the year the
message was sent, MM is the month, DD is the day, hh is the hour, mm is
the minute and ss is the second. This date and time are given in the
timezone where the message was sent. TZ is the timezone the date is
valid for. It must be of the form "+hhmm" or "-hhmm", where hh is the
number of hours offset from UTC and mm is the number of minutes
offset. Symbolic timezones are not permitted. The timezone specification
is recommended but optional, since it is not always available.

Clients should display this information as the date and time a text was
written, since the imported text will have been created at a later
time. The date and time when the mesage was imported would then be
displayed elsewhere or not at all.

@item mx-message-id [22] (text)

Data is the @code{Message-ID} header of an imported e-mail, with
whitespace and comments removed. The Message-ID should contain the
surrounding angles.

@item mx-in-reply-to [23] (text)

Data is a string containing one item of the same form as the
mx-message-id item described above. This is the Message-ID of
another mail the current text is a comment to.

Hopefully, this information comes from the @code{In-Reply-To} header
of the imported e-mail, but it could also have been picked from the end
of the @code{References} header line.

If the text really comments more than one other text directly, 
it is allowed to attach more than one @aux{mx-in-reply-to} items to
it.

@item mx-misc [24] (text)

Data is a string that contains all of the headers of an imported email,
including @code{Subject}, and including those that are redundantly
stored in other aux-items. The headers are concatenated with "\n". In
other words, this item contains all headers of an imported e-mail as
they appear in the message.

Clients are encouraged to provide a command to display this information.

@item mx-allow-filter [25] (conference, letterbox)

This aux-item has been declared obsolete. It was intended to supply
the importer with information on how to filter incoming messages
based on regular expressions matching header lines.

@item mx-reject-forward [26] (conference, letterbox)

This aux-item has been declared obsolete. It was intended 
to supplement mx-allow-filter by telling where rejected mails should
be sent.

@item notify-comments [27] (letterbox)

Data is a decimal text number that the user is interested in. Clients
should monitor this text for unread comments and present these to the
user in some convenient manner. This is typically used by users that
want to read comments to some text of theirs as soon as they arrive,
rather than in the normal reading order.

This item can only be set by the owner of the letterbox. No flags are
forced or cleared.

@item faq-for-conf [28] (text)

Data is a decimal number specifying the conference a certain text is a
FAQ for. The special number zero denotes that the text is a FAQ for the
entire system. Items of this kind can only be created by the LysKOM
server itself. Texts with this item are protected from garbage
collection.

@item recommended-conf [29] (server)

Data is a decimal number specifying a conference that new members should
automatically be added to, optionally followed by a space and a
recommended priority, optionally followed by a space and a membership
type.  In the future, additional data may be defined; clients should
be prepared to accept and ignore a space and any trailing data that may
follow the membership type.

A few examples might clarify what the data may look like:
@table @code
@item 1
Conference number 1.
@item 2 32
Conference number 2, with priority 32.
@item 3 250 11100000
Conference number 3, with priority 250.  The membership should be
secret, passive and have the invitation bit set.
@item 4 253 01000000 garbage
Conference number 4, with priority 253.  The membership should be
passive.  The client should ignore the trailing garbage.  Note that
clients are not allowed to create aux-items of this format, but the
should be prepared to hande them correctly.
@end table

This is a recommendation only; it is up to the client that creates a new
person to also add him to the conferences that are specified via
@aux{recommended-conf}.

@item allowed-content-type [30] (conference, letterbox, server)

Data is a non-negative decimal priority number, followed by a space,
followed by a LysKOM content type glob pattern.  Clients should send
texts to a conference only if the content-type matches any of the
@aux{allowed-content-type} glob patterns of that conference.

If the conference doesn't have any @aux{allowed-content-type}, the
@aux{allowed-content-type} items of the server should be used.  If the
server also has no @aux{allowed-content-type} aux-items, it should be
interpreted as if a single @aux{allowed-content-type} aux-item with the
value @samp{1 text/plain} exists.

If there are @aux{allowed-content-type} aux-items with different
priority numbers, it is a hint to the client about which content-type is
most desirable.  Content-types that matches a lower priority number are
preferred.

As an example, consider a conference with the following four
@aux{allowed-content-type} aux-items:

@example
1 text/plain
2 x-kom/basic
2 text/enriched
3 text/*
@end example

These aux-items taken together means that @samp{text/plain} is
preferred, that @samp{x-kom/basic} and @samp{text/enriched} can be
used if there is a reason why @samp{text/plain} is inadequate, and
that any text type (such as @samp{text/html}) is acceptable.  Other
content types, such as @samp{x-kom/user-area}, should not be used.

The server does not currently enforce the above restriction on the
content type of new texts.  This mechanism is currently a hint to the
client (or to the author of a new text).  This may change in the
future, if experience shows that it is desirable to have the server
enforce the content type.

@end table

@node Client-Specific Aux-Item Types
@subsection Client-Specific Aux-Item Types

Client-specific items do not cause the server to perform any magic. All
the flags (except the delete flag) are left untouched, the data is not
validated in any way, and anyone can create any item. If you need more
server support than this, your item should be on the predefined list.

All tags in the range 10000-19999 are reserved for clients. Blocks of
100 numbers at a time can be assigned to specific clients. A client
should never create items with tags in a range assigned to another
client or in an unassigned range. Assigned ranges will never change.

Currently, the following ranges are assigned to clients:
@itemize @bullet
@item 10000-10099: The Elisp Client