SGML: RS/RE Processing

Subject: Re: Treatment of RS/RE

Date: 30 Sep 1996 10:29:31 -0700

From: jenglish@crl.com (Joe English)

Newsgroup: comp.text.sgml



Chris Arena  <ccarena@pims01.psf.lmco.com> wrote:
>
>I am having some trouble understanding the rules for treatment of RS/RE
>in SGML.

So are we all...

>Is there a good text, thread, or FAQ which unambiguously explains the
>rules?

=========================================================================

Michael Sperberg-McQueen, Charles Goldfarb and James Clark came up with a
very good summary of the rules on the w3c-sgml mailing list a while ago:


| RE is insignificant (i.e. not passed to any downstream application,
| not part of the grove plan) when it occurs in any of the following
| patterns:
|
|   start-tag nondata* RE
|   RE nondata* end-tag
|   RS nondata+ RE
|
| where nondata is defined as:
|
|   nondata ::=
|                comment declaration
|              | processing instruction
|              | marked section declaration start
|              | marked section end
|              | included subelement
|              | shortref use declaration
|              | link set use declaration
|
|   marked section declaration start ::=
|                marked section start
|              , status keyword specification
|              , dso


Noting that the determination of when an RE is insignificant
is one of the last phases of parsing; it takes place after
all entity, character, and short references have been replaced
and after omitted start- and end-tags have been inferred.

The first pattern:

|   start-tag nondata* RE

removes the first record-end in an element's content;
the pattern:

|   RE nondata* end-tag

removes the last.  The third pattern:

|   RS nondata+ RE

discards record-ends from input lines containing nothing
but "nondata".


--Joe English

  jenglish@crl.com