MIMESGML Working Group                                D. Stinchfield
INTERNET-DRAFT                                        EBT, Inc.    
<draft-ietf- ?????? >                             
Expires May 31, 1996                                  December 1, 1995


          Using Catalogs and MIME to Exchange SGML Documents


Status of this Memo

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Distribution of this document is unlimited. Please send comments to the 
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Abstract

This draft proposes a standard for exchanging SGML documents over the 
World Wide Web using catalogs and MIME.  This draft extends SGML Open's 
definition of catalogs [10] by adding to it new keywords and storage 
object identifier (SOI) types. The new keywords identify SGML document 
objects (such as document type declarations and document entities), non-
SGML document objects (such as stylesheets), and management information 
(such as base URL, character encoding, and character repertoire).  The 
new SOI types include URIs and MIME Content-IDs.  This document also 
describes a new MIME content type called Application/SGML-Catalog which 
identifies a MIME body part as a catalog.



Revision History

Changed Application/Catalog to Application/SGML-Catalog, makes more 
sense.

Changed the syntax of Notation and added more to the description

Added ENCODING and CHARREP keywords.

Added host name suffix to Contend-ID values in examples.

Removed the keywords: CHARSET, BASESET, and CAPACITY.  Will assume that 
the public id's used to define them in the SGML declaration will be 
unique within the catalog.

Changed BASEURL to BASE and added to the definition so that BASE can now 
be either an absolute URL or an absolute filename.

Added a better description of how system identifiers are to be handled.

TR9401:1995 is being referenced instead of TR9401:1994.

User defined keywords are no longer required to begin with "X-" or "x-", 
but it is strongly recommended.

Noted how parameter entities are to be treated.

Added appendix D, public identifiers for Notations.

Added a new keyword called LinkType.



1. Introduction	4
1.1 Overview	4
1.2 SGML document Components	5
2. Catalog Description	5
2.1 Resolving System Identifiers	6
2.2 Parameter Entity Names	6
2.3 Catalog Keywords	6
2.3.1 SGMLDECL	7
2.3.2 DOCUMENT	7
2.3.3 DOCTYPE	7
2.3.4 PUBLIC	8
2.3.5 ENTITY	9
2.3.6 NOTATION	9
2.3.7 LINKTYPE	10
2.3.8 SEMANTICS	10
2.3.9 BASE	10
2.3.10 OVERRIDE	11
2.3.11 ENCODING	11
2.3.12 CHARREP	11
2.3.13 User Defined Keywords	11
2.4 Storage Object Identifiers	12
2.4.1 URIs as SOIs	12
2.4.2 The Content-ID SOI	12
3. Export Catalog Syntax	13
4. Application/SGML-Catalog	15
5. Examples	16
5.1 Sending Only A Catalog	16
5.1.1 MIME Message Content	17
5.2 Sending a Catalog and the Document Entity	17
5.2.1 MIME Message Content	18
5.3 Sending a Catalog and All Document Components	18
5.3.1 MIME Message Content	18
5.4 Sending a Catalog for a Single Non-Document Entity	20
6. Security Considerations	21
7. Acknowledgments	21
8. References	21
9. Authors' Address	22
10. Appendix A: SGML declaration Used In The Examples	23
10.1 SGML declaration	23
11. Appendix B: DTD Used In The Examples	25
11.1 DTD	25
12. Appendix C: SGML document Used In The Examples	26
12.1 SGML document entity	26
12.2 Entity Named "Legal"	26
12.3 Entity Named "MyEnding"	26
13. Appendix D: NOTATIONS	27
13.1 Usefule Notations	27
13.2 ISO 9070 Public Identifiers for NOTATIONs	27



1. Introduction

This draft proposes a standard for exchanging SGML documents over the 
World Wide Web using catalogs and MIME.  This draft extends SGML Open's 
definition of catalogs [10] by adding to it new keywords and storage 
object identifier (SOI) types. The new keywords identify SGML document 
objects (such as document type declarations and document entities), non-
SGML document objects (such as stylesheets), and management information 
(such as base URL, character encoding, and character repertoire).  The 
new SOI types include URIs and MIME Content-IDs.  This document also 
describes a new MIME content type called Application/SGML-Catalog which 
identifies a MIME body part as a catalog.

SGML catalogs were introduced in the SGML Open document entitled "Entity 
Management" [10] (also referred to as TR9401).  Catalog entries, as 
described in the SGML Open document, provide a mapping of PUBLIC 
external identifiers and entity names to system-dependent SOIs (these 
system-dependent SOIs are typically filenames, see section 2.2 for 
details).  This system-dependent requirement is too restrictive and 
fails to meet the needs of the internet community.  Specifically, SGML 
Open's catalog definition does not provide keyword entries for all the 
types of external objects used in SGML and it does not define how to map 
catalog entries to system-independent SOIs such as URLs.  This document 
addresses both of these limitations by extending SGML Open's catalog 
definition to include keywords for SGML external identifiers and by 
defining system-independent SOIs.   

Some key benefits to using catalogs and MIME to exchange SGML documents 
are:

     o a client only needs a catalog to begin processing, 
       it simply fetches the components referenced in the 
       catalog as they are needed;
     o a client that understands catalogs has a way to fetch 
       components of a document that it doesn't already have;
     o document components do not have to be modified in order 
       to be referenced in a catalog;
     o components of a document can be distributed across 
       many servers;
     o catalogs do not depend on MIME, therefore, they can be 
       used in other packaging schemes;
     o the impact on MIME is minimized;
     o catalogs are an implemented, proven technology;
     o a document's system identifiers can be referenced 
       in a catalog  and subsequently resolved by a client.



1.1 Overview

The new catalog keywords defined in this document are NOTATION, BASE, 
SEMANTICS, OVERRIDE, ENCODING, and CHARREP.  NOTATION came from Charles 
Goldfarb's paper entitled "Entity Management in SGML" [11] and refers to 
the SGML NOTATION declaration (refer to [3], page 426 for a description 
of NOTATION).  The others are described for the first time in this 
document:  BASE is used to resolve relative URLs found in a catalog;  
SEMANTICS is used to reference semantic processing information, such as 
stylesheets;  OVERRIDE indicates which TR9401 processing mode should be 
used to resolve external identifiers;  ENCODING describes the encoding 
of the catalog entries;  and CHARREP describes the character repertoire 
(refer to [3] page 193 for a detailed description of character 
repertoire) of the catalog entries.

User defined keywords are allowed in catalogs for experimental purposes.  
It is strongly recommended that user defined keywords begin with "X-" or 
"x-" and be located at the end of the catalog - this will make it easy 
for clients to identify user defined keywords.
  
System-independent SOIs are defined to permit both URIs and MIME 
Content-IDs.  The usefulness of URIs is evident from the popularity of 
the World Wide Web refer to [7] [8] [12] and [4] for detailed 
descriptions of URIs, URNs, and URLs.  An SOI that is defined to be a 
MIME Content-ID identifies a document component that is contained in a 
MIME body part (refer to [13] for a description of MIME Content-IDs).  A 
catalog that contains a MIME Content-ID SOI is typically part of a 
multipart message and usually refers to a body part contained in the 
same multipart message.

There are a number of ways to serve up an SGML document using catalogs 
and MIME.  The server could deliver just a catalog;  the server could 
deliver a catalog and a document entity;  the server could deliver a 
catalog and all of the document's components; the server could deliver a 
catalog and a non-document entity - detailed examples of all of these 
can be found in section 5.  Any catalog served using MIME will have a 
Content-Type of Application/SGML-Catalog.



1.2 SGML document Components

SGML documents are typically made up of a number of components.  Some of 
the components contain instructions to the SGML parser (such as the SGML 
declaration and the DTD) while others contain marked up text (such as 
the SGML document entity), and still others contain non-SGML data (such 
as figures).  These components can be identified in a number of 
different ways using what SGML calls external identifiers.  Catalog 
entries, among other things, identify SGML document components.

See ISO 8879:1986 [14] and to Charles Goldfarb's "The SGML Handbook" [3] 
for a rigorous description of SGML.

2. Catalog Description

A catalog provides a mapping between external object identifiers (such 
as public identifiers and entity names) to SOIs.  In TR9401 [10] an SGML 
system's entity manager typically treats SOIs as system-dependent 
filenames.  This is too restrictive for SGML Systems that need to take 
advantage of the Internet. Formally extending the meaning of SOIs to 
include Universal Resource Identifiers (URI, [7]) removes this system-
dependent restriction.  Catalogs that contain these types of SOIs are 
system-independent and so give flexibility to SGML systems.

To interchange an SGML document means to send a catalog and a set of 
zero or more components to a client (note, the interchange package could 
contain all of the document's components).  The catalog contains 
references to document components (refer to section 2.1 for a detailed 
list of keywords).  

2.1 Resolving System Identifiers

Entity references that are declared with system identifiers in an SGML 
document can be referenced in a catalog.  The logic that creates the 
catalog should set OVERRIDE to "YES" to indicate to the receiving 
systems that the catalog should be used to resolve external identifiers 
whether or not there is a system identifier defined for the external 
identifier in the document.  If the URL in the catalog is relative then 
it is resolved with respect to the BASE catalog entry.  If there's no 
BASE entry then the relative URL is resolved with respect to the URL of 
the catalog.  

What happens if there is no catalog entry for the entity?  If there is a 
system identifier for it in the document then the system identifier is 
used to resolve the reference.  If the system identifier is relative 
then it is resolved with respect to the entity in which the entity 
declaration is specified.



2.2 Parameter Entity Names

Parameter entity names always begin with a percent sign (%) as defined 
in TR9401:

 "Note that, if the entity name is a parameter entity name 
  (as opposed to a general entity name), an initial percent sign(%), 
  is part of the name.  (The percent sign- which is the reference
  concrete syntax replacement for the "PERO" character- shall be 
  used in the catalog regardless of the concrete syntax of the 
  current document.)"

2.3 Catalog Keywords

A catalog contains entries for SGML document components.  The order of 
the entries in the catalog is not important.  All entries are optional.  
A catalog can contain multiple entries with the same keyword.  The 
following keywords are defined in this document:

      SGMLDECL - SGML declaration
      DOCUMENT - SGML document entity
      DOCTYPE - Document type declaration (DTD)
      PUBLIC - public external identifier
      ENTITY - entity name
      NOTATION - notation name
      LINKTYPE - link type name
      SEMANTICS - name and type of the semantic information
      BASE - base URL
      OVERRIDE - defines which TR9401 processing mode to use
      CHARREP - character set
      ENCODING - character encoding
	X- or x- - user defined keyword prefix

These keywords are necessary to keep the name spaces of an SGML document 
separate.  An SGML document may contain many components, each of which 
can be identified by a local name (such as "chap1") or by a global 
"public identifier" (such as ISBN, URN, etc.).  Local identifiers may be 
re-used for different kinds of components.  For example, an SGML 
document could have an included entity called "footnote" and a special 
notation called "footnote".  In a catalog these could be represented by 
the following entries:

     ENTITY   "footnote"  "http://blah.com/blah.foot"
     NOTATION "footnote "http://blah.com/notation/yuk.not"

2.3.1 SGMLDECL

The SGML declaration is part of the SGML document and is required by the 
SGML parser before it can begin parsing.  The SGML declaration defines, 
among many other things, the SGML document's character set and the 
character strings that define the markup.  For an excellent description 
of SGML declarations refer to Wayne Wohler's paper called "SGML 
declarations" [1].  Appendix A of this document contains an example of 
an SGML declaration.  If an SGML document is not explicitly associated 
with an SGML declaration then a default SGML declaration is assumed by 
the parser.  

The SGML declaration is identified in the catalog by the SGMLDECL 
keyword.  An SGML declaration is not always self-contained.  It can 
include references to public identifiers ([3], 378). The following 
parameters of an SGML declaration can be defined as public identifiers: 
BASESET ([3], 453:12); CAPACITY ([3], 456:2); and SYNTAX ([3], 458:2).  
This proposal assumes that the public identifiers used for these 
parameters will be unique within the catalog;  more than likely BASESET, 
CAPACITY, and SYNTAX will be formal public identifiers which guarantees 
universal uniqueness (for a description of formal public identifiers 
refer to [3] pg 381).

The SGML declaration catalog keyword has the following syntax:

   sgmldecl = ("SGMLDECL", ps+,
                storage object identifier)


2.3.2 DOCUMENT

The DOCUMENT catalog keyword refers to the SGML document entity ([3], 
142:1).  The SGML document entity describes the first entity of the SGML 
document ([3], 142:1).  It typically contains a reference to a DTD, a 
document type declaration subset ([3], 404:6), and marked-up text.  
Appendix C of this document contains an example of an SGML document 
entity.  The syntax for DOCUMENT follows:

     DOCUMENT   = ("DOCUMENT", ps+,   
                     storage object identifier) 



2.3.3 DOCTYPE

The DOCTYPE catalog keyword refers to the Document type declaration 
(DTD) ([3], p402).  The syntax for DOCTYPE is:

     doctype  = ("DOCTYPE", ps+,     
                  document type name, ps+, 
                  storage object identifier) 

The value of the "document type name" is defined in the SGML document 
entity, for example the first line in the Document entity used in the 
examples looks like this:

     <!DOCTYPE MEMO  "/usr/wcs/dtd/memo.dtd" >

A catalog entry for it would look something like this:

     DOCTYPE  "MEMO"       "../../dtds/memo.dtd"

Note how the name, "MEMO", is defined in the document and referenced in 
the catalog.  The entity manager resolves a reference to the DTD by 
looking its name up in the catalog.  Appendix B of this document 
contains an example of a DTD.

It is not uncommon for the document's DTD to have both a public 
identifier and a system identifier:

     <!DOCTYPE MEMO  PUBLIC "-//EBT//DTD Released Memo//EN"     
                         "/usr/wcs/dtds/memo.dtd" [...] > ...

For these cases the server decides whether or not to include both in the 
catalog.  If it decides to include both then the catalog entries for 
them would look something like this:

     DOCTYPE  "MEMO"  "http:/www.bill.com/usr/wcs/dtds/memo.dtd"
     PUBLIC   "-//EBT//DTD Released Memo//EN"    
                      "http://www.yoman.edu/pub/dtds/memo.dtd"

The client decides which definition to use first.



2.3.4 PUBLIC

PUBLIC catalog keywords refer to public identifiers that are defined in 
the DTD or in the Document entity's "document type declaration subset".  
The syntax for the PUBLIC keyword is:

     public = ("PUBLIC", ps+, 
                public identifier, ps+, 
                storage object identifier) 

Here's an example of a parameter entity declaration that contains a 
public identifier:

<!ENTITY % ISOnum PUBLIC 
           "ISO 8879-1986//ENTITIES Numeric and Special Graphic//EN">

a catalog entry for the above public identifier might look like this:

PUBLIC  "ISO 8879-1986//ENTITIES Numeric and Special Graphic//EN"      
        "http://www.wcs.com/usr/wcs/isonum.ent"


2.3.5 ENTITY

The ENTITY catalog keyword refers to document entities that are 
defined/referenced in the document but have no public identifiers.  The 
syntax for the ENTITY keyword is:

     entity = ("ENTITY", ps+, 
                entity name, ps+, 
                storage object identifier) 

The following are examples of entity declarations for system 
identifiers:

     <!ENTITY  Legal    SYSTEM  >
                and
     <!ENTITY  MyEnding SYSTEM "/usr/des/ending.sgm"  >

Entries in a catalog for these would look something like this:

     ENTITY   "Legal"      "http://www.bill.com/company/legal.sgm"
     ENTITY   "MyEnding"   "http://www.bill.com/ending.sgml"


2.3.6 NOTATION

The NOTATION catalog keyword refers to data content notations 
defined/referenced in the document.  The syntax for NOTATION is (note, 
the storage object identifier is optional for NOTATION):

     notation = ("NOTATION",  ps+, 
                  notation name
                  [ ,ps+, storage object identifier ]
                 )

The following example illustrates how NOTATION could be used for Java 
scripts:

<!NOTATION JuggleBalls SYSTEM "java/juggleballs.java">
<!ELEMENT Juggler - O CDATA>
<!ATTLIST Juggler notation NOTATION JuggleBalls>

<Juggler notation=JuggleBalls>

             input to JuggleBalls script, for example: specify number 
             of items and juggling style.

A catalog entry for the NOTATION declaration described above would look 
like:

     NOTATION  "JuggleBalls"  "http://www.bill.com/juggleballs.java"

Processing of notations are system dependent - there's no way for a 
server to guarantee that a client can process a specific notation.  The 
NOTATION keyword in the catalog may only give a hint, and possibly a 
pointer to a notation processor.  Note, it can be dangerous for the 
client to resolve a reference to a notation processor - loading and 
running a notation processor (remote script) from a remote, and 
potentially unsecured site is dangerous!  However, in a secure 
environment exchanging scripts may be perfectly safe.    

Appendix D describes a collection of public identifiers for NOTATIONS as 
described by ISO 9070.  These are not yet approved by ISO, but hopefully 
they will be soon.

Unfortunately ISO 9070 does not define public identifiers for some of 
the more popular NOTATIONS found on the Web such as Postscript, TeX, and 
Tcl.  Formal Public Identifiers for these can also be found in Appendix 
D.

2.3.7 LINKTYPE

The syntax for LinkType is:

     linktype  = ("LINKTYPE", ps+,     
                  link type name, ps+, 
                  storage object identifier) 

For a detailed description of what an SGML linktype is refer to [14] and 
[3].

2.3.8 SEMANTICS

There may be semantic information, such as stylesheets, associated with 
a document.  Semantic information is not required for parsing the 
document and can be ignored by the client.  However, it is often 
required that a client be able to access appropriate semantic 
specifications.  The syntax for the SEMANTICS keyword is:

     semantics = ("SEMANTICS", ps+, 
                   semantic name, ps+, 
                   semantic type, ps+, 
                   storage object identifier) 

Here's an example of an entry in a catalog for semantic information:

     SEMANTICS "large-print"  "DSSSL" 
        "http://www.bill.com/style/large.sty"



2.3.9 BASE

Relative URLs [4] are allowed in SOIs.  Relative URLs can be resolved 
using the BASE keyword catalog entry.  If there's no BASE in the catalog 
then the URL for the catalog is used for relative URL resolution.  The 
syntax for the BASE keyword is:

     base = ("BASE", ps+, absoluteURL) 

Here's an example of an entry in a catalog for BASE:

     BASE  "http://www.bill.com/docs/memo/mine/dummy"



2.3.10 OVERRIDE

The OVERRIDE keyword defines which TR9401 processing mode to use when 
the SGML system is resolving external identifiers with explicit system 
identifiers.  When OVERRIDE is "YES" then the receiving system should 
use the catalog to resolve external identifiers whether or not there is 
a system identifier defined for it in the document.  If the value for 
OVERRIDE is "NO" then system identifiers found in the document should be 
used first to resolve external identifiers.

The syntax for the OVERRIDE keyword is:

     override = ("OVERRIDE", ps+, ("YES" | "NO"))

2.3.11 ENCODING

The ENCODING keyword is specified as:

        encoding = ("ENCODING", ps+, alphanumeric+)
  
The ENCODING keyword indicates the encoding of proceeding catalog 
entries.  There can be more than one ENCODING entry in a catalog.  When 
an ENCODING entry is found it supersedes the value of any preceding 
ENCODING entry.  For example, the following catalog describes catalog 
entries that have different encodings:

ENCODING "SHIFT-JIS"
DOCUMENT  "http://www.goeast.com/anaxi.sgm"
ENCODING "ISO-10646-UTF7"
DOCTYPE  "MEMO"       "http://www.gowest.com/dtds/memo.dtd"
ENCODING "SHIFT-JIS"
ENTITY   "MyEnding"   "http://www.goeast.com/ending.sgml"
ENTITY   "Legal"      "http://www.goeast.com/company/legal.sgm"

Here the document entity and the entities MyEnding and Legal are encoded 
in SHFIFT-JIS while the DTD is encoded in ISO-10646-UTF7.


2.3.12 CHARREP

The CHARREP keyword specifies the character repertoire(s)for the catalog 
entries that follow it. The syntax of the CHARREP keyword is:

        charrep = ("CHARREP", +(ps+, alphanumeric+) )

Like ENCODING, the CHARREP keyword stays in effect until a new CHARREP 
keyword is detected (the values in the new CHARREP replace the values of 
the previous CHARREP entry).  Note, there can be more than one value in 
a CHARREP entry.  For example:
 
        CHARREP   "JIS 0208" "JIS 0201"


2.3.13 User Defined Keywords

A user can create new catalog keywords by beginning the keyword with 
either an "X-" or an "x-".  Users may do this to test experimental 
keywords. User defined keywords are only allowed at the end of the 
catalog and must begin with either the "X-" or the "x-" prefix.


2.4 Storage Object Identifiers

As described in TR9401 [10], an SOI  "is expected to be a string that is 
assumed to make sense to the operating system involved, i.e., it should 
name a file accessible from the current file system" [10].  TR9401 
anticipated the extension of SOIs to define "a different or extended 
meaning that will require the recognition and special processing of 
certain characters in the SOI." [10].  Two such SOI extensions are 
defined in this section.  The first defines SOIs in terms of URIs and 
the second defines them in terms of a MIME Content-ID.  The latter type 
of SOI is used to identify the body part of a Multipart/Related message.  
Content-ID referencing is used when a single Multipart/Related message 
contains the document's catalog and one or more of the document's 
components (see 5.2 and 5.3 for examples).  The syntax for an SOI is:

     storage object identifier =
            uri object identifier            |
            content id object identifier     |
            TR9401 storage object identifier

The term "TR9401 storage object identifier" refers to the TR9401's 
definition of an SOI and is included here for backwards compatibility.


2.4.1 URIs as SOIs

URIs are used to describe the names and locations of objects. Uniform 
Resource Locators  (URL) and Uniform Resource Names  (URN) are examples 
of  URIs (refer to [8] and [12] for rigorous descriptions of URLs and 
URNs).

Generally speaking URLs have the following structure:

      scheme:scheme-specific-part   

A scheme is associated with a protocol such as http or ftp (refer to [8] 
for a list of schemes supported by a URL).  The scheme-specific-part 
contains the information required by the scheme to locate the object.

"The purpose or function of a URN is to provide a globally unique, 
persistent identifier used for recognition, for access to 
characteristics of the resource or for  access to the resource itself." 
[12]  There is no internet standard defined for URNs yet, but one is 
anticipated soon.



2.4.2 The Content-ID SOI

In addition to the catalog a server can send some/all of the document's 
components in a single MIME message. Content-ID SOIs are used to map 
entries in the catalog to the body part of the MIME message that 
contains the corresponding component.  See the examples in 5.2 and 5.3.  
The syntax for Content-ID based SOIs is:

     content id object identifier = 
                    "Content-ID" ":" msg-id ; as defined in RFC 1521 
[13] 
     msg-id      =  "<" addr-spec ">"       ; as defined in RFC 822 [15]
                                            ; Unique message id
     addr-spec   =  local-part "@" domain   ; as defined in RFC 822 [15]
                                            ; global address
     local-part  =  word *("." word)        ; as defined in RFC 822 [15]
                                            ; uninterpreted
                                            ; case-preserved
     domain      =  sub-domain *("." sub-domain)
                                            ; as defined in RFC 822 [15]
     sub-domain  =  domain-ref / domain-literal
						        ; as defined in RFC 822 [15]
     domain-ref  =  atom                    ; as defined in RFC 822 [15]
                                            ; symbolic reference

3. Export Catalog Syntax

export catalog = 
   ( catalog entry, ps+ )+, ( user defined, ps+ )*

catalog entry  = 
          sgmldecl     |
          document     |
          doctype      |
          public       |
          entity       |
          notation     |
          semantics    |
          linktype     |
          base         |
          override     |
          user defined |
          charrep      |
          encoding

sgmldecl = ("SGMLDECL", ps+,
             storage object identifier)

DOCUMENT= ("DOCUMENT", ps+,
            storage object identifier) 

doctype  = ("DOCTYPE", ps+,   
             document type name, ps+,  
             storage object identifier) 

public   = ("PUBLIC", ps+,    
             public identifier, ps+,   
             storage object identifier) 

entity   = ("ENTITY", ps+,    
             entity name, ps+,  
             storage object identifier) 

notation = ("NOTATION", ps+, 
             notation name [, ps+,
             storage object identifier] )
 
linktype = ("LINKTYPE", ps+,     
             link type name, ps+, 
             storage object identifier) 

semantics= ("SEMANTICS",ps+, 
             semantic name, ps+, 
             semantic type, ps+,
             storage object identifier) 

base     = ("BASE",  ps+, absoluteURL) 

override = ("OVERRIDE", ps+, ("YES" | "NO"))

charrep  = ("CHARREP", +(ps+, alphanumeric+))

encoding = ("ENCODING", ps+, alphanumeric+)

user defined = (("X-" | "x-"), alphanumeric+) 


storage object identifier =
          uri object identifier        |
          content id object identifier |
          TR9401 storage object identifier

uri object identifier = 
          as defined in RFCs 1808[4], 1630[7], 1738[8]  

content id object identifier = 
              "Content-ID" ":" msg-id  ; as defined in RFC 1521 [13] 

msg-id      =  "<" addr-spec ">"       ; as defined in RFC 822 [15]
                                       ; Unique message id
addr-spec   =  local-part "@" domain   ; as defined in RFC 822 [15]
                                       ; global address
local-part  =  word *("." word)        ; as defined in RFC 822 [15]
                                       ; uninterpreted
                                       ; case-preserved
domain      =  sub-domain *("." sub-domain)
                                       ; as defined in RFC 822 [15]
sub-domain  =  domain-ref / domain-literal
                                       ; as defined in RFC 822 [15]
domain-ref  =  atom                    ; as defined in RFC 822 [15]
                                       ; symbolic reference

TR9401 storage object identifier = 
          "storage object identifier" as defined in TR9401 [10]

semantic name = alphanumeric+

absoluteURL = see "absoluteURL" in RFC 1808 [4]

document type name = alphanumeric+

; From TR9401 [10]
ps = s | comment

LIT  = `"`      ; the double quote

LITA = "`"      ; the single quote

comment = COM, system character*, COM

COM  = "--"

entity name   = 
          extended name character+              |
          (LIT, extended name character+, LIT)  |
          (LITA, extended name character+, LITA)


The following notes are taken from TR9401 [10]:

(1.) public identifier and s are defined in 8879 (and RS, RE, SPACE and 
SEPCHAR are as in the reference concrete syntax of 8879);

(2.) extended name character means (a) in the case of an undelimited 
string, any character except the "null" character, the LIT character, 
the LITA character,  and those characters allowed in s, and (b) in the 
case of a delimited literal, any character except the "null" character 
and the delimiting character for that literal (i.e., LIT or LITA);

(3.) system character means (a) in the case of an undelimited string, 
any character except the "null" character, the LIT character, the LITA 
character, and those characters in s; (b) in the case of delimited 
literal, any character except the "null" character and the delimiting 
character for the literal (i.e., LIT or LITA); (c) in the case of a 
comment, any character except the "null" character and a sequence of 
characters that would be interpreted as the terminating COM delimiter; 
(d) in the case of an undelimited string the comprises the keyword and 
the second and subsequent argument of other information, the string must 
not be recognizable as the PUBLIC or ENTITY keywords.


4. Application/SGML-Catalog

A new MIME Content-Type called Application/SGML-Catalog identifies a 
MIME body part for a catalog 

               MIME type name:          Application
               MIME subtype name:       SGML-Catalog
               Required parameters:     none
               Optional parameters:     charset
               Encoding considerations: may be encoded
               Security considerations: see section 4 below
               Published specification:
               Person and email address to contact for further 
information:
                             D. Stinchfield <des@ebt.com>

       Use the Application/SGML-Catalog media-type for catalogs.
       The structure and use of catalogs is defined in this 
specification.


5. Examples

The SGML document used in all the examples is composed of the following:

     o an SGML declaration, defined in Appendix A;
     o a Document type declaration (DTD), defined in Appendix B;
     o an SGML document entity, defined in Appendix C;
     o two SGML entities, defined in Appendix C;
     o a figure entity, not defined in this draft.

In all examples the components of this SGML document are spread across 
multiple servers, except for the example entitled "Sending a Catalog and 
All of its Components", where  all of the document's are contained in a 
single MIME message. 

Each example defines its own unique catalog.  The catalog varies from 
example to example depending on the number of document components sent 
along with it.  Remember, by definition zero or more components are sent 
along with the catalog.  The sender decides how many components to 
include in the MIME message.  

A document component that's not included in the MIME message can be 
resolved by the client in one of two ways: 1.) the client has the 
component cached; 2.) the client requests the component using the SOI 
defined for it in the catalog.

The definitions for the following external identifiers are not included 
in this document:

     formal public identifiers 
          ISO 646:1983//
              CHARSET International Reference Version (IRV)//
              ESC 2/5 4/0 
          ISO 8879-1986//
              ENTITIES Numeric and Special Graphic//EN

	system identifier
           ../style/all.sty" - DSSSL style sheet

Examples that contain a Multipart/Related MIME Content Type default the 
compound object's "root" to the first body part of the message [5] which 
is always of type Application/SGML-Catalog.


5.1 Sending Only A Catalog

In this example only the catalog is sent to the client. If the client's 
SGML System is capable of handling URIs that are defined as SOIs then 
the newly received catalog can be passed, without modification, to the 
client's SGML System. If the client's SGML System cannot handle this 
type of SOI then the client must do some pre-processing before passing 
the catalog on.  The pre-processing logic should do something like the 
following:

     1.  fetch all of the components referenced in the catalog, 
     2.  store the components locally, and 
     3.  update the catalog (change all URI based SOIs).

A server may have a number of reasons why it would want/need to send 
only a catalog:

     o  The server only stores catalogs, it does not store 
        any document components;
     o  The client may have requested only the catalog.  Perhaps 
        the client wants to compare the contents of this catalog 
        with the contents of a different catalog.  Or maybe the 
        client already has most, if not all, of the document's 
        components cached;
     o  The server may want to keep network traffic down by increasing
        the likelihood that the client will get a cache hit on 
        catalog entries.



5.1.1 MIME Message Content

MIME-Version: 1.0
Content-Type: Application/SGML-Catalog; charset=us-ascii
     
SGMLDECL "http://www.ebt.com/decl/ebtsgml.dcl"
OVERRIDE "YES"
PUBLIC   "ISO 646:1983//CHARSET 
         International Reference Version (IRV)//ESC 2/5 4/0" 
         "http://www.iso.ch/charset/6461983.cha"
PUBLIC   "ISO Registration Number 100//CHARSET 
         ECMA-94 Right-hand Part of Latin Alphabet Nr.1//ESC 2/13 4/1" 
         "http://www.iso.ch/charset/ecma94.cha"
PUBLIC   "-//EBT//CAPACITY CoolCaps 1.0//"   
         "http://www.ebt.com/decl/coolcaps.cap"
PUBLIC   "-//EBT//SYNTAX  SinSyn 0.1//"      
         "http://www.ebt.com/decl/syntax/sinsyn.syn"
BASE  "http://www.bill.com/docs/memo/mine/dummy"
DOCUMENT  "anaxi.sgm"
DOCTYPE  "MEMO"       "../../dtds/memo.dtd"
PUBLIC   "ISO 8879-1986//ENTITIES Numeric and Special Graphic//EN"    
         "http://www.wcs.com/usr/wcs/isonum.ent"
ENTITY   "%ISOnum"    "http://www.wcs.com/usr/wcs/isonum.ent"
ENTITY   "MyEnding"   "ending.sgml"
ENTITY   "Legal"      "../company/legal.sgm"
SEMANTICS "large-print"  "DSSSL"   "../style/all.sty"



5.2 Sending a Catalog and the Document Entity

This example describes how to send a catalog and a document entity 
component using a Multipart/Related message [5].  This example is the 
likely scenario for Web-based Browsers where simultaneous rendering and 
resolving of external identifiers are necessary. The document entity 
will likely contain enough text for the Browser to render meaningful 
text to the user, but it won't include the many entities that the text 
may link to.  These external identifiers, like figures, can be resolved 
(fetched, that is) by the entity manager while the application is 
rendering the text or (as for hyperlinked information) on user demand.


5.2.1 MIME Message Content

MIME-Version: 1.0
Content-Type: Multipart/Related; boundary=let-go-of-my-leg; 
              type="Application/SGML-Catalog"

--let-go-of-my-leg
Content-Type: Application/SGML-Catalog; charset=us-ascii

SGMLDECL "http://www.ebt.com/decl/ebtsgml.dcl"
OVERRIDE "YES"
PUBLIC   "ISO 646:1983//CHARSET 
         International Reference Version (IRV)//ESC 2/5 4/0"
         "http://www.iso.ch/charset/6461983.cha"
PUBLIC   "ISO Registration Number 100//CHARSET 
         ECMA-94 Right-hand Part of Latin Alphabet Nr.1//ESC 2/13 4/1" 
         "http://www.iso.ch/charset/ecma94.cha"
PUBLIC   "-//EBT//CAPACITY CoolCaps 1.0//"   
         "http://www.ebt.com/decl/coolcaps.cap"
PUBLIC   "-//EBT//SYNTAX  SinSyn 0.1//"      
         "http://www.ebt.com/decl/syntax/sinsyn.syn"
BASE  "http://www.bill.com/docs/memo/mine/dummy"
DOCUMENT  "Content-ID:<bookemdano@toons.com>"
DOCTYPE  "MEMO"       "../../dtds/memo.dtd"
PUBLIC   "ISO 8879-1986//ENTITIES Numeric and Special Graphic//EN"    
         "http://www.wcs.com/usr/wcs/isonum.ent"
ENTITY   "%ISOnum"    "http://www.wcs.com/usr/wcs/isonum.ent"
ENTITY   "MyEnding"   "ending.sgml"
ENTITY   "Legal"      "../company/legal.sgm"
SEMANTICS "large-print"  "DSSSL"   "../style/all.sty"

--let-go-of-my-leg
Content-Type: Application/SGML; charset=us-ascii
Content-ID: <bookemdano@toons.com>

include document entity from Appendix C
--let-go-of-my-leg--
     

5.3 Sending a Catalog and All Document Components

Like the previous example, sending a catalog and all of the document's 
components is described using a Multipart/Related message. A server 
might do something like this in response to a client's request for all 
of the document components to be sent with the catalog.


5.3.1 MIME Message Content

MIME-Version: 1.0
Content-Type: Multipart/Related; boundary=go-speed-racer; 
              type="Application/SGML-Catalog"

--go-speed-racer
Content-Type: Application/SGML-Catalog; charset=us-ascii

SGMLDECL "Content-ID:<joejitsu@toons.com >"
OVERRIDE "YES"
PUBLIC   "ISO 646:1983//CHARSET 
         International Reference Version (IRV)//ESC 2/5 4/0" 
         "Content-ID:<mumbles@toons.com >"
PUBLIC   "ISO Registration Number 100//CHARSET 
         ECMA-94 Right-hand Part of Latin Alphabet Nr.1//ESC 2/13 4/1" 
         "Content-ID:<underdog@toons.com >"
PUBLIC   "-//EBT//CAPACITY CoolCaps 1.0//" 
         "Content-ID:<mastercylinder@toons.com >"
PUBLIC   "-//EBT//SYNTAX  SinSyn 0.1//"  
         "Content-ID:<lippythelion@toons.com >"
DOCUMENT  "Content-ID:<andhardyharhar@toons.com >"
DOCTYPE  "MEMO"       "Content-ID:<mahilagorilla@toons.com >"
PUBLIC   "ISO 8879-1986//ENTITIES Numeric and Special Graphic//EN"    
         "Content-ID:<mrpeebles@toons.com >"
ENTITY   "%ISOnum"    "Content-ID=<wallygator@toons.com >"
ENTITY   "MyEnding"   "Content-ID:<mrwhoopy@toons.com >"
ENTITY   "Legal"      "Content-ID:<johnnyquest@toons.com >"
SEMANTICS "large-print"  "DSSSL"  "Content-
ID:<hodgyandbandit@toons.com>"

--go-speed-racer
Content-Type:Application/SGML; charset=us-ascii
Content-ID:"<joejitsu@toons.com>"

description of SGML declaration from Appendix A is included here

--go-speed-racer
Content-Type:Application/SGML; charset=us-ascii
Content-ID:"<mumbles@toons.com >"

ISO 646 character set definition included here

--go-speed-racer
Content-Type:Application/SGML; charset=us-ascii
Content-ID:"<mastercylinder@toons.com >"

description of Capacity from Appendix A is included here

--go-speed-racer
Content-Type:Application/SGML; charset=us-ascii
Content-ID:"<lippythelion@toons.com >"

description of Syntax from Appendix A is included here

--go-speed-racer
Content-Type:Application/SGML; charset=us-ascii
Content-ID:"<underdog@toons.com >"

Contents of ISO Registration Number 100//CHARSET ECMA-94 Right-hand Part 
of Latin Alphabet Nr.1//ESC 2/13 4/1 included here

--go-speed-racer
Content-Type: Application/SGML; charset=us-ascii
Content-ID: <andhardyharhar@toons.com >

include Document entity as described in Appendix C

--go-speed-racer
Content-Type: Application/SGML; charset=us-ascii
Content-ID: <mahilogorilla@toons.com >

include DTD as described from Appendix B

--go-speed-racer
Content-Type: Application/SGML; charset=us-ascii
Content-ID: <mrpeebles@toons.com >

ISO 8879-1986 Entity set included here

--go-speed-racer
Content-Type: Application/SGML; charset=us-ascii
Content-ID: <wallygator@toons.com >

include entity set defined for %ISOnum

--go-speed-racer
Content-Type: Application/SGML; charset=us-ascii
Content-ID: <mrwhoopy@toons.com >

include entity MyEnding as described in Appendix C

--go-speed-racer
Content-Type: Application/SGML; charset=us-ascii
Content-ID: <johnnyquest@toons.com >

include entity Legal as described in Appendix C

--go-speed-racer
Content-Type: Application/SGML; charset=us-ascii
Content-ID: <hodgyandbandit@toons.com >

included here is a bunch of DSSSL-Lite

--go-speed-racer--


5.4 Sending a Catalog for a Single Non-Document Entity

This example describes what a server may send in response to a request 
for a non-document entity.  All of the previous examples assume that the 
original request was for the document entity.  SGML documents can get 
very deep and have a large number of external identifiers referenced in 
it.  Likewise, the complete catalog for a document could also get very 
large (a "complete catalog" contains all of the external identifiers 
referenced in all of the document's entities).  There is no reason why 
the complete catalog has to be sent with the document entity.  All 
that's required are enough entries in the catalog for the client system 
to resolve references declared in the entity being transferred.  For 
example, Appendix C.2 defines an entity called "Legal" which includes a 
reference to an entity called "MyEnding".  A request for "Legal" would 
result in a Multipart/Related message that looks like this:

     MIME-Version: 1.0
     Content-Type: Multipart/Related; boundary=let-go-of-my-leg; 
                   type="Application/SGML-Catalog"

     --let-go-of-my-leg
     Content-Type: Application/SGML-Catalog; charset=us-ascii

     BASE  "http://www.bill.com/docs/memo/mine/dummy"
     OVERRIDE "YES"
     ENTITY   "Legal" "Content-ID:<bookemdano@toons.com >"
     ENTITY   "MyEnding"   "ending.sgml"

     --let-go-of-my-leg
     Content-Type: Application/SGML; charset=us-ascii
     Content-ID: <bookemdano@toons.com >

     include entity "Legal" from Appendix C.2
     
     --let-go-of-my-leg--



6.  Security Considerations

SGML documents, like other compound documents, may contain entities 
whose media-types present security concerns, e.g. 
Application/PostScript.  Further, SGML may contain explicit processing 
instructions for a presentation or composition system; use of such 
instructions present concerns similar to those of 
Application/PostScript.

The use of active media-types with Notation declarations can provide an 
opportunity for the sender to execute a script or other code on the 
recipient's machine.



7.  Acknowledgments

Thanks go to Andre Alguero, Steve DeRose, Chris Maden, Gavin Nicol, and 
Bill Smith here at EBT for helping me with the content and structure of 
this document.  Thanks to Ed Levinson for the many discussions and 
debates that helped me to clarify (I hope) many of the ideas contained 
in this document.  Thanks also go out to Wayne Wohler of IBM for his 
help on SGML declarations, a most confusing topic.  Thanks to James 
Clark for his help on general SGML issues.  Thanks to Martin Bryan for 
his help on Notations.



8.  References

[1] Wayne Wohler, "SGML declarations",   
    http://www.sil.org/sgml/wlw11.html
[2] Eric van Herwijnen, "Practical SGML", Second Edition, 
    Kluwer Academic Publishers, 1994, ISBN 0-7923-9434-8
[3] Charles F. Goldfarb, "The SGML Handbook", 
    Oxford University Press, 1994, ISBN 0-19-853737-9
[4] R. Fielding, "Relative Uniform Resource Locators", RFC 1808
[5] E. Levinson, "The MIME Multipart/Related Content-Type", RFC ????
[6] Daniel W. Connolly, HTML 2.0 SGML declaration found at 
    http://www.w3.org/hypertext/WWW/MarkUp/html-spec/html.decl
[7] T. Berners-Lee, "Universal Resource Identifiers in WWW: 
    A Unifying Syntax for the Expression of Names and Addresses of
    Objects on the Network as used in the World-Wide Web", RFC 1630
[8] T. Berners-Lee, L. Masinter, and M. McCahill, 
    "Uniform Resource Locators (URL)", RFC 1738
[10] Paul Grosso, "Entity Management", SGML Open 
     Technical Resolution 9401:1995 (Amendment 1 to TR9401)
[11] Charles F. Goldfarb, "Entity Management in SGML", 11/30/93
[12] Sollins, K. and Masinter, L., 
     "Functional Requirements for Uniform Resource Names", RFC 1737
[13] N.Borenstein, "MIME (Multipurpose Internet Mail Extensions) 
     Part One: Mechanisms for Specifying and Describing the Format of
     Internet Message Bodies", RFC 1521
[14] "ISO 8879:1986 Information processing - The and office systems -
     Standard Generalized Markup Language (SGML)", 
     Geneva, 15 October 1986
[15] D. H. Crocker, "Standard for the Format of ARPA Internet Text
     Messages", RFC 822



9. Authors' Address

Don Stinchfield
Electronic Book Technologies, Inc.
One Richmond Square
Providence, RI  02906
(401) 421-9550 x280
des@ebt.com



10. Appendix A: SGML declaration Used In The Examples

This Appendix contains the definitions for the SGML declaration, for the 
CAPACITY parameter, and for the SYNTAX parameter. The SGML declaration 
is a modified version of the one used for HTML 2.0 [6] -  I changed the 
CAPACITY and SYNTAX declarations so that they referenced public 
identifiers.  The following external identifiers are reference in the 
SGML declaration:

     o  BASESET "ISO 646:1983//
             CHARSET International Reference Version (IRV)//
             ESC 2/5 4/0"
     o  BASESET  "ISO Registration Number 100//
             CHARSET ECMA-94 Right-hand Part of Latin Alphabet Nr.1//
             ESC 2/13 4/1"
     o  CAPACITY   PUBLIC "-//EBT//CAPACITY CoolCaps 1.0//"
     o  SYNTAX  PUBLIC "-//EBT//SYNTAX  SinSyn 0.1//"



10.1 SGML declaration

<!SGML  "ISO 8879:1986"
--
	Copied this from the SGML declaration for HyperText Markup 
Language (HTML).
--

CHARSET
         BASESET  "ISO 646-1983//CHARSET
                   International Reference Version
                   (IRV)//ESC 2/5 4/0"
         DESCSET  0   9   UNUSED
                  9   2   9
                  11  2   UNUSED
                  13  1   13
                  14  18  UNUSED
                  32  95  32
                  127 1   UNUSED
         BASESET  "ISO Registration Number 100//CHARSET
                  ECMA-94 Right-hand Part of
                  Latin Alphabet Nr.1//ESC 2/13 4/1"

         DESCSET  128  32   UNUSED
                  160  96    160

CAPACITY   SGMLREF
           TOTALCAP        150000
           GRPCAP          150000
           ENTCAP          150000

SCOPE      DOCUMENT
SYNTAX
           SHUNCHAR CONTROLS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
		 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 127
           BASESET  "ISO 646-1983//CHARSET
                   International Reference Version
                   (IRV)//ESC 2/5 4/0"
           DESCSET  0 128 0
           FUNCTION
		      RE          13
                  RS          10
                  SPACE       32
                  TAB SEPCHAR  9
	

           NAMING   LCNMSTRT ""
                  UCNMSTRT ""
                  LCNMCHAR ".-"
                  UCNMCHAR ".-"
                  NAMECASE GENERAL YES
                           ENTITY  NO
           DELIM    GENERAL  SGMLREF
                  SHORTREF SGMLREF
           NAMES    SGMLREF
           QUANTITY SGMLREF
                  ATTSPLEN 2100
                  LITLEN   1024
                  NAMELEN  72    -- somewhat arbitrary; taken from
                                internet line length conventions --
                  PILEN    1024
                  TAGLVL   100
                  TAGLEN   2100
                  GRPGTCNT 150
                  GRPCNT   64         
          

FEATURES
  MINIMIZE
    DATATAG  NO
    OMITTAG  YES
    RANK     NO
    SHORTTAG YES
  LINK
    SIMPLE   NO
    IMPLICIT NO
    EXPLICIT NO
  OTHER
    CONCUR   NO
    SUBDOC   NO
    FORMAL   YES
  APPINFO    "SDA"  -- conforming SGML document Access application
--
>


11. Appendix B: DTD Used In The Examples

The DTD listed  below is a modified version of  the one found on page 33 
of Eric van Herwijnen's book called "Practical SGML" [2].  The following 
external identifier is used in the DTD:

     <!ENTITY % ISOnum PUBLIC  
                "ISO 8879-1986//
                ENTITIES Numeric and Special Graphic//EN" 
                "/usr/wcs/isonum.ent" >

The above definition is for a parameter entity and it contains both a 
public identifier and a system identifier. The examples have both in the 
catalog.
  

11.1 DTD

<!--  DTD for simple office memoranda                            -->
<!ENTITY % doctype "MEMO"  -- document type generic identifier -->
<!--        ELEMENTS    MIN     CONTENT      (EXCEPTIONS)        -->
<!ELEMENT   %doctype;   - -    ((TO & FROM),  BODY, CLOSE?)        >
<!ELEMENT   TO          - O    (#PCDATA)                           >
<!ELEMENT   FROM        - O    (#PCDATA)                           >
<!ELEMENT   BODY        - O    (P)*                                >
<!ELEMENT   P           - O    (#PCDATA | Q)*                      >
<!ELEMENT   PREF        - O    EMPTY                               >
<!ELEMENT   Q           - -    (#PCDATA)                           >
<!ELEMENT   CLOSE       - -    (#PCDATA)                           >
<!--        ELEMENTS    NAME   VALUE               DEFAULT       -->
<!ATTLIST   %doctype    STATUS (CONFIDEN|PUBLIC)   PUBLIC          >
<!ATTLIST   P           id     ID                  #IMPLIED        >
<!ATTLIST   PREF        refid  IDREF               #IMPLIED        >
<!ENTITY    %  ISOnum PUBLIC "ISO 8879-1986//ENTITIES Numeric and 
Special Graphic//EN" 
"/usr/wcs/isonum.ent">
%ISOnum;


12. Appendix C: SGML document Used In The Examples

The SGML document defined in this appendix is broken up into 3 parts: an 
SGML document entity and two SGML Entities.  The SGML document entity 
contains references to external identifiers in the DOCTYPE and ENTITY 
declarations:

     o  This one contains both a public identifier and a 
        system identifier:

             <!DOCTYPE MEMO  PUBLIC "-//EBT//DTD Released Memo//EN"                
                                    "/usr/wcs/dtd/memo.dtd" [...] >

     o  This ENTITY declaration has system identifier and a 
        system identifiers parameter:

             <!ENTITY  MyEnding SYSTEM "/usr/des/ending.sgm"  >

     o  This one specifies a system identifier without specifying a 
        system identifier parameter (this is provided for in the SGML
        Standard for implementors that want to resolve System 
        Identifiers from the entity name alone [3, p378]):

             <!ENTITY  Legal SYSTEM  >


12.1 SGML document entity

<!DOCTYPE MEMO  PUBLIC 
     "-//EBT//DTD Released Memo//EN"  
     "/usr/wcs/dtd/memo.dtd" [
<!ENTITY  Legal     SYSTEM  >
<!ENTITY  MyEnding  SYSTEM "/usr/des/ending.sgm"  >
] >
<MEMO>
<TO>Anaximander
<FROM>Cool Papa Shad
<BODY>
&Legal;
<P>Yo Anax, you've got a bizarre name!</P>
<P>&MyEnding;</P>
</BODY>
</CLOSE>
</MEMO>



12.2 Entity Named "Legal"

<P>If you or anyone you know tries to read this email then you're in 
really big trouble!</P>
<P>You know this is the end of the document when you see &MyEnding;</P> 



12.3 Entity Named "MyEnding"

<Q>Regards, Don</Q>



13. Appendix D: NOTATIONS
13.1 Usefule Notations
For TeX I have taken the ISBN from Donald Knuth's book "The TeXbook" to 
create the Formal Public Identifier:

<!NOTATION TEX PUBLIC
     "ISBN 0-201-13448-9:://NOTATION TeX//EN"  >

DVI???

For PostScript I have taken the ISBN number for the PostScript reference 
manual to create a Formal Public Identifier:

<!NOTATION POSTSCRIPT PUBLIC 
           "ISBN 0--201--18127--4::Adobe//NOTATION PostScript//EN" >


For Tcl I have taken the ISBN number from John K. Ousterhout's book "Tcl 
and the Tk Toolkit" to create a Formal Public Identifier:
 
<!NOTATION TCL  PUBLIC 
           "ISBN 0-201-63337-X::Addison-Wesley//NOTATION Tcl//EN"

13.2 ISO 9070 Public Identifiers for NOTATIONs

SGML Notation Declarations for ISO-defined Data Notations
----------------------------------------------------------
<!-- (C) International Organization for Standardization 199?
     Permission to copy in any form is granted with
     conforming SGML systems and applications as defined
     in ISO 8879, provided this notice is included in all
     copies.                                             -->
<!-- ISO standard data notations. Typical invocation:
     <!ENTITY % ISOdata PUBLIC "ISO/IEC TR ????:????//ELEMENTS Data
                                Notations Standardized by ISO//EN" >
       %ISOdata;
-->
<!NOTATION FORTRAN  PUBLIC "ISO/IEC 1539:1991//NOTATION
                            Information technology -
                            Programming languages -
                            FORTRAN//EN"                           >
<!NOTATION COBOL    PUBLIC "ISO 1989:1985//NOTATION
                            Programming languages -
                            COBOL//EN"                             >
<!NOTATION PL/1     PUBLIC "ISO 6160:1979//NOTATION
                            Programming languages -
                            PL/1//EN"                              >
<!NOTATION PASCAL   PUBLIC "ISO 7185:1990//NOTATION
                            Programming languages -
                            Pascal//EN"                            >
<!NOTATION GKS      PUBLIC "ISO 7942:1985//NOTATION
                            Information processing systems -
                            Computer graphics -
                            Graphical Kernel System (GKS)
                            functional description//EN"            >
<!NOTATION APL      PUBLIC "ISO 8485:1989//NOTATION
                            Programming languages -
                            APL//EN"                               >
<!NOTATION ODAafp   PUBLIC "ISO/IEC 8613-9:1993//NOTATION
                            Information technology -
                            Open Document Architecture (ODA)
                            and Interchange Format - Part 9:
                            Audio formatted processable content
                            architecture//EN"                      >
<!NOTATION ODA      PUBLIC "ISO/IEC 8613-10:1991//NOTATION
                            Information processing -
                            Text and office systems -
                            Office Document Architecture (ODA)
                            and interchange format -
                            Part 10: Formal specifications//EN"    >
<!NOTATION ODAvfp   PUBLIC "ISO/IEC 8613-15:1995//NOTATION Video
                            formatted processable content architecture">
<!NOTATION CGMchar  PUBLIC "ISO/IEC 8632-2:1992//NOTATION
                            Information technology -
                            Computer graphics -
                            Metafile for the storage and transfer of
                            picture description information -
                            Part 2: Character encoding//EN"        >
<!NOTATION CGMbin   PUBLIC "ISO/IEC 8632-3:1992//NOTATION
                            Information technology -
                            Computer graphics -
                            Metafile for the storage and transfer of
                            picture description information -
                            Part 3: Binary encoding//EN"           >
<!NOTATION CGMclear PUBLIC "ISO/IEC 8632-4:1992//NOTATION
                            Information technology -
                            Computer graphics -
                            Metafile for the storage and transfer of
                            picture description information -
                            Part 4: Clear text encoding//EN"       >
<!NOTATION ADA      PUBLIC "ISO 8652:1987//NOTATION
                            Programming languages -
                            Ada//EN"                               >
<!NOTATION GKS-3D   PUBLIC "ISO 8805:1988//NOTATION
                            Information technology -
                            Computer graphics -
                            Graphical Kernal System
                            for Three Dimensions (GKS-3D)//EN"     >
<!NOTATION ASN1     PUBLIC "ISO/IEC 8824:1990//NOTATION
                            Information technology -
                            Open Systems Interconnection -
                            Specification of Abstract Syntax
                            Notation One (ASN.1)//EN"              >
<!NOTATION SGML     PUBLIC "ISO 8879:1986//NOTATION
                            Information processing -
                            Text and office systems -
                            Standard Generalized Markup Language
                            (SGML)//EN"                            >
<!NOTATION RT-comms PUBLIC "ISO/IEC 9066-2:1989//NOTATION
                            Text communication -
                            Reliable transfer -
                            Part 2: Protocol specification//EN"    >
<!NOTATION RO-comms PUBLIC "ISO/IEC 9072-2:1989//NOTATION
                            Text communication -
                            Remote operation -
                            Part 2: Protocol specification//EN"    >
<!NOTATION SDIF     PUBLIC "ISO/IEC 9069:1988//NOTATION
                            Information processing -
                            SGML support facilities -
                            SGML Document Interchange Format
                            (SDIF)//EN"                            >
<!NOTATION SQL      PUBLIC "ISO/IEC 9075:1992//NOTATION
                            Information technology -
                            Database languages - SQL//EN"          >
<!NOTATION ISO9282  PUBLIC "ISO/IEC 9282-2:1992//NOTATION
                            Information Processing -
                            Coded representation of pictures -
                            Part 2: Incremental encoding of point
                            lists in a 7-bit or 8-bit
                            environment//EN"                       >
<!NOTATION fonts    PUBLIC "ISO/IEC 9541-2:1991//NOTATION
                            Information technology -
                            Font information interchange -
                            Part 2: Interchange Format//EN"        >
<!NOTATION ISOmath  PUBLIC "ISO/IEC TR9573-7:????//NOTATION
                            Information processing -
                            SGML support facilities -
                            Techniques for using SGML -
                            Mathematics Markup//EN"                >
<!NOTATION ISOchem  PUBLIC "ISO/IEC TR9573-7:????//NOTATION
                            Information processing -
                            SGML support facilities -
                            Techniques for using SGML -
                            Chemistry Markup//EN"                  >
<!NOTATION PHIGS-2  PUBLIC "ISO/IEC 9592-2:1989//NOTATION
                            Information processing -
                            Computer graphics -
                            Programmer's Hierarchical Interactive
                            Graphics System (PHIGS) -
                            Part 2: Archive file format//EN"       >
<!NOTATION PHIGS-3  PUBLIC "ISO/IEC 9592-3:1989//NOTATION
                            Information processing -
                            Computer graphics -
                            Programmer's Hierarchical Interactive
                            Graphics System (PHIGS) -
                            Part 3: Clear-text encoding of
                            archive file//EN">
<!NOTATION PHIGS-4  PUBLIC "ISO/IEC 9592-4:1992//NOTATION
                            Information processing -
                            Computer graphics -
                            Programmer's Hierarchical Interactive
                            Graphics System (PHIGS) -
                            Part 4: Plus Lumiere und Surfaces,
                            PHIGS PLUS//EN">
<!NOTATION EDIFACT  PUBLIC "ISO 9735:1988//NOTATION
                            Electronic data interchange for
                            administration, commerce and transport
                            (EDIFACT) -
                            Application level syntax rules//EN"    >
<!NOTATION C        PUBLIC "ISO/IEC 9899:1990//NOTATION
                            Programming languages - C//EN"         >
<!NOTATION MOTIS    PUBLIC "ISO/IEC 10021:1990//NOTATION
                            Text communication -
                            Message-Oriented Text Interchange
                            Systems (MOTIS) - Part 6: Protocol
                            Specifications//EN">
<!NOTATION DOAM     PUBLIC "ISO/IEC 10031-2:1991//NOTATION
                            Information technology -
                            Text and office systems -
                            Distributed-office-applications model -
                            Part 2: Distinguished object reference
                            and associated procedures//EN">
<!NOTATION DFR      PUBLIC "ISO/IEC 10166-2:1991//NOTATION
                            Information technology -
                            Text and office systems -
                            Document Filing and Retrieval (DFR) -
                            Part 2: Protocol Specification//EN"    >
<!NOTATION DPA      PUBLIC "ISO/IEC 10175:????//NOTATION
                            Document Printing Application
                            (DPA)//EN"                             >
<!NOTATION DSSSL    PUBLIC "ISO/IEC 10179:????//NOTATION
                            Information processing -
                            Text and office systems -
                            Document Style Semantics and
                            Specification Language (DSSSL)//EN"    >
<!NOTATION SPDL     PUBLIC "ISO/IEC 10180:1995//NOTATION
                            Information technology -
                            Text communication -
                            Standard Page Description Language
                            (SPDL)//EN"                            >
<!NOTATION BASIC    PUBLIC "ISO/IEC 10279:1991//NOTATION
                            Information technology -
                            Programming languages -
                            Full BASIC//EN"                        >
<!NOTATION ISO10367 PUBLIC "ISO/IEC 10367:1991//NOTATION
                            Information technology -
                            Standardized coded graphic character
                            sets for use in 8-bit codes//EN"       >
<!NOTATION RDT      PUBLIC "ISO/IEC 10740-2:1993//NOTATION
                            Information technology -
                            Text and office systems -
                            Referenced Data Transfer -
                            Part 2: Protocol specifications//EN"   >
<!NOTATION HyTime   PUBLIC "ISO/IEC 10744:1992//NOTATION
                            Information technology -
                            Hypermedia/Time-based Structuring
                            Language (HyTime)//EN"                 >
<!NOTATION JPEG     PUBLIC "ISO/IEC 10918:1993//NOTATION
                            Digital Compression and Coding of
                            Continuous-tone Still Images
                            (JPEG)//EN"                            >
<!NOTATION MPEG1vid PUBLIC "ISO/IEC 11172-2:1993//NOTATION
                            Information technology -
                            Coding of moving pictures and associated
                            audio for digital storage media at up to
                            about 1,5 Mbit/s -
                            Part 2: Video//EN"                     >
<!NOTATION MPEG1aud PUBLIC "ISO/IEC 11172-3:1993//NOTATION
                            Information technology -
                            Coding of moving pictures and associated
                            audio for digital storage media at up to
                            about 1,5 Mbit/s -
                            Part 3: Audio//EN"                     >
<!NOTATION MPEG2vid PUBLIC "ISO/IEC 13818-2:1995//NOTATION
                            Information technology -
                            Coding of moving pictures and associated
                            audio: Part 2. Video//EN"              >
<!NOTATION MPEG2aud PUBLIC "ISO/IEC 13818-3:1995//NOTATION
                            Coding of moving pictures and associated
                            audio: Part 3. Audio//EN"              >
<!NOTATION JBIG     PUBLIC "ISO/IEC 11544:1993//NOTATION
                            Information technology -
                            Coded representation of picture
                            and audio information -
                            Progressive bi-level image
                            compression//EN"                       >
<!NOTATION MHEG     PUBLIC "ISO/IEC 13522:????//NOTATION
                            Information technology -
                            Coded representation of multimedia
                            and hypermedia information objects
                            (MHEG)//EN"                            >
<!NOTATION IGES     PUBLIC "-//NBS IR 88-3813//NOTATION Initial
                            Graphics Exchange Specification
                            (IGES)//EN"                            >
<!NOTATION G4-fax   PUBLIC "-//CCITT VII.3 T 6//NOTATION Blue book -
                            Terminal equipment and protocols for
                            telematic services - Facsimile encoding
                            schemes and coding control functions for
                            group 4 facsimile apparatus//EN"       >
<!NOTATION G3-fax   PUBLIC "-//CCITT VII.3 T 4//NOTATION Red book -
                            Terminal equipment and protocols for
                            telematic services - Facsimile encoding
                            schemes and coding control functions for
                            group 3 facsimile apparatus//EN"       >
<!NOTATION CCITT4-1 PUBLIC "-//CCITT VII.3 T 6//NOTATION Group 4
                            Facsimile Type 1 Untiled Raster//EN">
<!NOTATION CCITT4-2 PUBLIC "-//CCITT VII.3 T 6//NOTATION Group 4
                            Facsimile Type 2 Tiled Raster//EN"   >
<!NOTATION ITU-601  PUBLIC "-//ITU::Recommendation 601//NOTATION
                            Definition of analogue/digital video
                            signals//EN"                           >
<!NOTATION ITU-709  PUBLIC "-//ITU::Recommendation 790//NOTATION
                            Basic parameter values for the HDTV
                            standard for international programme
                            exchange//EN"                          >
<!NOTATION ITU-G711 PUBLIC "-//ITU::G.711//NOTATION Pulse code
                            modulation (PCM) of voice
                            frequencies//EN"                       >
<!NOTATION ITU-G721 PUBLIC "-//ITU::G.721//NOTATION 32kbit/s
                            adaptive pulse code modulation
                            (ADPCM)//EN"                           >
<!NOTATION ITU-G722 PUBLIC "-//ITU::G.722//NOTATION 7kHz audio-coding
                            within 64kbit/s//EN"                   >
<!NOTATION ITU-J52  PUBLIC "-//ITU::J.52//NOTATION Digital
                            transmission of high quality sound
                            programme signals using one, two or
                            three 64kbit/s channels per mono signal
                            and up to six per stereo channel)//EN" >
<!NOTATION ITU-J80  PUBLIC "-//ITU::J.80//NOTATION Transmission of
                            component-coded digital TV signals
                            for contribution applications at bit
                            rates near 140 Mbit/s//EN"             >
<!NOTATION ITU-J81  PUBLIC "-//ITU::J.81//NOTATION Transmission of
                            component-codd digital TV signals for
                            contribution-quality applications at
                            the third hierarchical level of CCITT
                            (34-45 Mbit/s)//EN"                    >
<!NOTATION ITU-T100 PUBLIC "-//ITU::T.100//NOTATION Videotext//EN" >
<!NOTATION ITU-T120 PUBLIC "-//ITU::T.120//NOTATION Transmission
                            protocols for multimedia data
                            communications//EN"                    >
<!NOTATION ITU-F310 PUBLIC "-//ITU::F.310//NOTATION Broadband
                            Videotext//EN"                         >
<!NOTATION ITU-F821 PUBLIC "-//ITU::F.821//NOTATION Broadband
                            TV Distribution//EN"                   >
<!NOTATION ITU-F822 PUBLIC "-//ITU::F.822//NOTATION Broadband
                            HDTV Distribution//EN"                 >
<!NOTATION ITU-MDV  PUBLIC "-//ITU::MDV//NOTATION Multimedia
                            Delivery Service//EN"                  >
<!NOTATION ITU-MDD  PUBLIC "-//ITU::MDV//NOTATION Multimedia
                            Distribution Service//EN"              >
<!NOTATION ITU-MBTF PUBLIC "-//ITU::MBTF//NOTATION Multipoint
                            Binary File Transfer//EN"              >

<!NOTATION SMPTE125 PUBLIC "-//SMPTE::125M-1992//NOTATAION 10 Bit
                            Component Video Signal 4:2:2 -
                            Bit-Parallel Digital Interface//EN"    >
<!NOTATION SMPTE259 PUBLIC "-//SMPTE::259M-1993//NOTATION 10 Bit
                            4:2:2 Component and 4fsc NTSC Composite
                            Digital Signals - Serial Digital
                            Interface//EN"                         >
<!NOTATION S17.131  PUBLIC "-//SMPTE::S17.131//NOTATION Bit-Serial
                            Digital Interface for High-Definition
                            Television Systems//EN"                >
A. 
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