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RE: Read-only and removeChild/replaceChild

From: Joseph Kesselman <keshlam@us.ibm.com>
Date: Thu, 5 Jul 2001 14:01:37 -0400
To: WWW DOM <www-dom@w3.org>
Message-ID: <OF3469DE4D.DCD89D40-ON85256A80.0061E47E@pok.ibm.com>

>I have got to find a "Entity and EntityReference Objects for Dummies"
>document somewhere.

First question: How well do you understand XML entities in the first place?
Our objects are driven by what the XML Recommendation says about how
entities are used (http://www.w3.org/TR/REC-xml#sec-references) and defined
(http://www.w3.org/TR/REC-xml#sec-entity-decl). Entity References are bound
to the Entity definition which has the same name; that's built into the XML
spec and is handled automagically by the DOM.

Two complicating factors:

1) There isn't an API in DOM Level 1 or Level 2 for
creating/changing/removing Entity (definition) nodes. That's because those
versions of the DOM deliberately deferred most of DTD/Schema issues. We
provided a place for parsers to hang the data, but how it gets there was
deliberately left as implementation-specific pending DOM Level 3's
"abstract schema" support.

2)  As noted in the DOM spec, parsers are permitted to fully expand Entity
References -- replacing them with their value, rather than presenting that
value as children of an appropriate EntityReference node. If your parser is
doing this, you'll never see EntityReference nodes in your document tree
unless you create them explicitly. (There are arguments for and against
this expansion, depending on whether your application does or doesn't want
to know where the boundaries were... so the DOM deliberately left this
open. Some parsers actually let you pick which mode you prefer by setting a
flag before you parse.)

Hope that gets you pointed in the right direction.

Joe Kesselman  / IBM Research
Received on Thursday, 5 July 2001 14:02:13 UTC

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