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Report from the SGML ERB meeting of Oct. 9th



The SGML ERB met Wed. Oct 9th and voted on quite a few items.  In attendence: 
Bosak, Bray, Clark, DeRose, Hollander, Kimber, Maler, Paoli, Sperberg-McQueen, 
and Sharpe.  Absent: Magliery and Connolly.  By a recent resolution of the ERB, 
and at Dan Connolly's request, he is now a non-voting liaison member.  Thus, 
"Unanimous" means 10 in favor.  No votes were close enough that Tom's presence 
or absence would have made a difference.

Several issues were left unresolved at the end of the meeting; the ERB will be 
meeting tomorrow and Saturday to get through this stuff.

>A.1 XML will have only one concrete syntax, fixed at XML
>specification time, not document-instance parse time (0.2, 13.3,
>13.4).

Passed, Unanimous

>A.2 All or virtually all the information provided by a normal
>SGML declaration will be fixed for all documents; no SGML declaration
>will be necessary.  (Possible exception:  character-set information may
>vary document to document, but will be conveyed in other ways.)
>(6.2.3)

Passed, Unanimous

>A.3 XML will have no OMITTAG, DATATAG, SHORTREF, LINK, CONCUR,
>RANK, or SUBDOC features (7.3.1, 7.3.1.1, 7.3.1.2, 7.3.2, 7.4, 7.5, 7.6,
>7.7, 7.8, 9.4.6, 11.2, 11.5, 11.6, 13.5).

Passed, Unanimous

>A.4 XML will make only partial use of the SHORTTAG feature:
>
>  * no minimized start-tags or, probably, end-tags (7.4, 7.5)
>  * no omission of attribute name and value indicator (7.9.1.2)
>But
>  * omission of attribute-value specification will be legal for
>attributes not declared REQUIRED (7.9) (applies only when
>DTD is supplied and used)
>The final point, on omitted attribute-value specifications, raises the
>general question of how XML systems will behave when no DTD, or a
>partial DTD, is provided -- if such omitted or partial DTDs are allowed.
>It also raises the question of providing a way for a document to signal
>that its DTD can be skipped without loss of information (e.g. because it
>has no default attribute values, or no empty elements, etc.).  These
>questions are to be discussed and decided separately.

Passed, Unanimous

>A.5 XML will have no quantities or capacities (7.3.3, 7.4.2,
>7.9.2, 7.9.4.5, 9.4.1, 9.4.2, 9.8, 11.3.1, 13.2).

Passed, Unanimous

>A.6 XML will not allow asynchronous marked sections -- marked
>sections must begin and end in the same element.

Passed; Unanimous.  As Harvey Bingham pointed out, this needs careful phrasing
to avoid ambiguity.

>A.7 Should XML have CDATA, RCDATA, and TEMP marked sections or
>not?

XML will have CDATA marked sections, which must begin with the 9-character 
literal string "<![CDATA[" and end with the 3-character literal string "]]>".
This is essentially Charles Goldfarb's proposal, although we may not call them 
CLEARDATA.

XML will not have RCDATA or TEMP marked sections.

Both Unanimous.

>A.8 Should XML have INCLUDE and IGNORE marked sections or not?
>(If this question is answered YES, it leads to a separate question, how
>to achieve conditional inclusion in XML markup declarations.  This
>related question is to be decided separately.)

Split in two: XML will not have INCLUDE or IGNORE marked sections in document 
instances; Unanimous.  The question of conditional markup in declarations is 
still open.

>A.9 XML will have no CDATA or RCDATA elements (11.2.3).

Passed, Unanimous.

>A.10 How should XML escape markup delimiter characters in content
>(especially if (R)CDATA elements and marked sections are not
>allowed)?

Unanimously agreed that CDATA marked sections are to be used for blocks of 
text.  See A19 for more on this.

>A.11 XML will retain the distinction between element content and
>mixed content (7.6, 11.2.4).  (Applies only if DTD supplied and
>used.)

Passed, DeRose dissenting.

>A.12 XML will require all attribute-value specifications to take
>the form of attribute-value literals (7.9.3, 7.9.3.1).

Passed, Unanimous.

>A.13 XML will not allow RE to end an entity or character
>reference; an explicit refc must provided, and it must be a semicolon
>(9.4.4).

Passed, Unanimous.

>A.16 XML will stipulate that character references within
>processing instructions should be resolved by the XML parser (8).

Defeated, Sperberg-McQueen dissenting.

>A.18 XML will have declarations for elements, and attributes, but not for 
short-references or links (11.1).

Passed, Unanimous, for elements and attributes.  Notations and entities remain 
open.

>A.19 XML will retain fundamentally the same parsing rules as
>SGML, though they may be expressed differently.  (N.B. there is some
>sentiment for making XML's rules more restrictive than SGML's.)

Agreed unanimously that the rules should be stricter than SGML in that the 
characters '&', '<', and '>' are deemed always to delimit markup, and must 
always be escaped, specifically as "&amp;", "&lt;", and "&gt;", when appearing 
in parsed character data.  The ERB recognizes that this impinges on the user's 
name space in an un-SGML-like way, but feels that this has already, de facto, 
happened.

>A.21 like SGML, XML will forbid empty strings as attribute values
>for non-CDATA attributes, require FIXED attributes to take their default
>values (7.9.4.1, 7.9.4.2), and distinguish implied values from
>null-string values (11.3.4).

Passed, 7 in favor, DeRose, Hollander, and Sperberg-McQueen dissenting.

>A.23 XML will have no CURRENT attributes, but it will have FIXED,
>REQUIRED, and IMPLIED attributes, and attributes with explicit
>defaults.

Passed, Unanimous.

>A.24 Unlike SGML, XML will not allow direct references to
>external data entities from within parsed character data (9.4).

Passed, Unanimous.

>A.25 Like SGML, XML will forbid recursive entity reference
>(9.4).

Passed, Unanimous.

>A.26 Like SGML, XML will allow elements to be declared ANY
>(11.2.4).  (Whether other similar shorthand declarations will be
>defined, e.g. for any subelements but not allowing PCDATA, will be
>decided separately.)

Passed, Bray dissenting.

>A.27 XML will behave like SGML as regards behavior and precedence
>of occurrence indicators and connectors in content models (11.2.4.1,
>11.2.4.2).  (Whether to abolish the AND connector will be decided
>separately.)

Passed, Unanimous.


Cheers, Tim Bray
tbray@textuality.com http://www.textuality.com/ +1-604-488-1167


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