As per Relevance of the word entities, we have this rfc below:
Network Working Group E.
Request for Comments: 1874 Accurate Information Systems, Inc
Category: Experimental December 1995
SGML Media
Status of this
This memo defines an Experimental Protocol for the
community. This memo does not specify an Internet standard of
kind. Discussion and suggestions for improvement are requested
Distribution of this memo is unlimited
This document proposes new media sub-types of Text/SGML
Application/SGML. These media types can be used in the exchange
SGML documents and their entities. Specific details for the
or encapsulation of groups of related SGML entities using MIME
currently being considered by the mimesgml Working Group
internet@ebt.com>.
1.
A need exists for the transfer the elements of documents
using the Standard Generalized Markup Language (SGML) [ISO-8879].
While the specific details of such transfers are being
general agreement exists on the need to register basic media
for the SGML entities not covered by existing types
The Standard Generalized Markup Language (SGML) is used to
document structure and a rigorous description of it is left to [ISO
8879]. The terms used in the present document attempt to
consistent with SGML terminology and usage
2. The SGML Media-
There are two media-types for SGML parsable entities, Text/SGML
Application/SGML. Both have the same optional parameters. Text/
provides a fallback to Text/Plain for those without SGML capability
Senders should base the choice between text and application media
types on the entity's content. Text is suggested for entities
would be meaningful to a human being without SGML processing
Application/SGML is recommended for all others
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RFC 1874 SGML Media Types December 1995
2.1. Text/
MIME type name:
MIME subtype name:
Required parameters:
Optional parameters: charset, SGML-bctf, SGML-
Encoding considerations: may be
Security considerations: see section 4
Published specification: ISO 8879:1986
Person and email address to contact for further information
E. Levinson
The Text/SGML media-type can be employed when the contents of
SGML entity is intended to be read by a human and is in a
comprehensible form. That is the content can be easily discerned
someone without SGML display software. Each record in the
entity, delimited by record start (RS) and record end (RE) codes
must correspond to a line in the Text/SGML body part
SGML entities that do not meet the above requirements should use
Application/SGML media-type
See section 2.3 for a description of the parameters
2.2. Application/
MIME type name:
MIME subtype name:
Required parameters:
Optional parameters: SGML-bctf, SGML-
Encoding considerations: may be
Security considerations: see section 4
Published specification: ISO-8879
Person and email address to contact for further information
E. Levinson
Use the Application/SGML media-type for SGML text entities that
not appropriate for Text/SGML. When used, each record start (RS)
record end (RE) character shall be explicitly represented by the
combination specified in the SGML declaration
The parameters are described in the next section
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RFC 1874 SGML Media Types December 1995
2.3. SGML Sub-type
The parameters for the Text/ and Application/SGML subtypes
defined below
charset The charset parameter for Text/SGML is defined
[RFC-1521], the valid values and their meaning
registered by the Internet Assigned
Authority (IANA) [RFC-1590]. The default
value for all Text content-types is "us-ascii
[RFC-1521].
The charset parameter is provided to permit non
SGML capable systems to provide
behavior when Text/SGML defaults to Text/Plain
SGML capable systems will use the SGML-bctf param
eter
SGML-bctf The SGML-bctf (SGML bit combination
format) parameter describes the method used
transform the entity's sequence of constant
binary numbers (called "bit combinations" in [
8879, 4.24]) into the octet stream contained
the MIME body part
Valid values for SGML-bctf are the BCTF
names defined in Annex C of [ISO-10744] and
reproduced for convenience in the Appendix.
default value is "identity", i.e. perform
transformation
SGML-boot The SGML-boot parameter value is the content-ID
a MIME body part (Application/Octet-stream)
satisfies the requirements of the boot
in [ISO-10744]. The Appendix contains a
of those requirements. The SGML-boot parameter
only applicable if the SGML entity is a
entity
3. Security
SGML entities contain information to be parsed and processed by
recipient's SGML system. Those entities may contain and such
may permit explicit system level commands to be execute
processing the data. To the extent that an SGML system will
arbitrary command strings recipients of SGML entities may be at risk
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RFC 1874 SGML Media Types December 1995
Parsable SGML entities may also contain explicit
instructions for a presentation or composition system; use of
instructions present concerns similar to those
Application/PostScript
4.
[ISO-8879]
Information processing -- 8-bit Single-Byte Coded
Character Sets -- Part 1: Latin Alphabet No. 1,
8859-1:1987.
[ISO-8879]
ISO 8879:1986, Information processing -- Text and
systems -- Standard Generalized Markup Language (SGML).
[ISO-10744]
ISO/IEC 10744:1992, Information technology --
Hypermedia/Time-based Structuring Language (HyTime) (
modified by First Proposed Technical Corrigendum, ISO/
JTC1/SC18 N5027)
[RFC-1521]
Borenstein, N., and N. Freed, "MIME (Multipurpose
Mail Extensions) Part One: Mechanisms for Specifying
Describing the Format of Internet Message Bodies",
1521, Bellcore, Innosoft, September 1993.
[RFC-1590]
Postel, J., "Media Type Registration Procedure", RFC 1590,
USC/Information Sciences Institute, March 1994.
[RFC-1642]
Goldsmith, D., and M. Davis, "UTF-7, A Mail-
Transformation Format of UNICODE", RFC 1642, Taligent
Inc., July 1994.
5. Author's
Ed
Accurate Information Systems, Inc
2 Industrial
Eatontown, NJ 07724
EMail: ELevinson@Accurate.
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RFC 1874 SGML Media Types December 1995
ISO-10744 BCTF Values and Boot
A.1. Bit Combination Transformation Format (BCTF)
The following list of Bit Combination Transformation Format (BCTF
values is provided as a convenience. The authoritative source
[ISO-10744].
identity Each bit combination is represented by a
octet; this BCTF can be used only for entities
of whose bit combinations have a value not
255.
fixed-2 Each bit combination is represented by exactly 2
octets, with the more significant octet first;
BCTF can be used only for entities all of whose
combinations have a value not exceeding 65535.
fixed-3 Each bit combination is represented by exactly 3
octets, with a more significant octet preceding
less significant octets; this BCTF can be used
for entities all of whose bit combinations have
value not exceeding 16777215.
fixed-4 Each bit combination is represented by exactly 4
octets, with a more significant octet preceding
less significant octets
utf-8 Each bit combination is represented by a
number of octets according to UCS
Format 8 defined in Annex P to be added by the
proposed drafted amendment (PDAM 1) to ISO/
10646-1:1993.
utf-7 Each bit combination is represented by a
number of octets in the range 0 through 127
described in [RFC-1642]; this BCTF can be used
for entities all of whose bit combinations have
value not exceeding 65535.
euc-jp Each bit combination is treated as a pair of octets
most significant octet first, encoding a
using
Extended_UNIX_Code_Fixed_Width_for_Japanese charset
and is transformed into the variable length
of octets that would encode that character using
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RFC 1874 SGML Media Types December 1995
Extended_UNIX_Code_Packed_Format_for_Japanese char
set
sjis Each bit combination is treated as a pair of octets
most significant octet first, encoding a
using
Extended_UNIX_Code_Fixed_Width_for_Japanese charset
and is transformed into the variable length
of octets that would encode that character using
Shift_JIS charset
A.2. The Boot
The body part specified by the SGML-boot parameter contains
sequence of triplets of positive integers separated by white space
The triplets correspond to the described character set portion [IS0-
8879, 13.1.1.2] of the SGML declaration. SGML-boot provides
capability to identify the character set of the document's
declaration when it uses significant SGML characters [ibid., 4.298]
in the SGML reference concrete syntax [ibid., 13.4] that have
character number [ibid., 4.44] in the document's character set
differs from us-ascii. The default value is "0 128 0",
characters are us-ascii
Notes: (1) The triplet, has the following meaning
Starting with character number dscn in the us-ascii character set
renumber noc characters starting at bscn and incrementing by one
Thus, 0 128 0, represents the identity mapping. (2) The document'
declaration itself may also redefine the significant SGML characters
the boot attribute is intended to bootstrap the SGML system's
of the declaration
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if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
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