W3C home > Mailing lists > Public > w3c-sgml-wg@w3.org > December 1996

ERB decisions on RS/RE and whitespace

From: Tim Bray <tbray@textuality.com>
Date: Wed, 18 Dec 1996 11:17:13 -0800
Message-Id: <3.0.32.19961218111708.00a255d4@pop.intergate.bc.ca>
To: w3c-sgml-wg@w3.org
On December 18, the ERB took up the question of RS/RE and whitespace.  All
members were present except James Clark and Eve Maler.

The vote in favor of the following was unanimous.

XML processors, when operating without a DTD, are required to consider all 
bytes that are not markup to be data and to pass them to the application.  
When operating with a DTD, the processor may, but is not required to, pass on 
to the app white space known to be insigificant because it's in element content.  
In the case where it passes white space on, it must also inform the app that 
this is element content and so cannot be significant.

The XML Specification will contain an appendix which provides a set of 
recommendations which, if followed by authors, will ensure that they
get a parse tree that will be the same whether or not the DTD is taken
into consideration.  We didn't discuss the exact contents of this: it
will include at least [a] no white space where it might be element
content and [b] no defaulted attributes; careful attention will be
required from everyone on the list to make sure we get this right.

The -XML-SPACE attribute will be retained, but its role becomes advisory;
an XML processor will always pass the data as noted above, and must also
pass the value of -XML-SPACE when specified.  The allowed values of -XML-SPACE
change to "PRESERVE" and "DEFAULT".  Formally

   -XML-SPACE (PRESERVE|DEFAULT) #IMPLIED

PRESERVE is a signal from the author to the application that all the whitespace 
bytes are to be considered significant.  DEFAULT means that the application's
default handling is considered OK.  The attribute's value is considered to
be inherited by descendent elements of an element for which it's specified.
For the root element, the default is DEFAULT.  It is an error, in the context
of a DTD, for an element with element content to have -XML-SPACE="PRESERVE".

Further discussion of these issues is unlikely to be read by anyone
in their right mind.

Cheers, Tim Bray
tbray@textuality.com http://www.textuality.com/ +1-604-488-1167
Received on Wednesday, 18 December 1996 14:25:04 EST

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