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Re: OT: Schemas and entities

• To: Nathan Shaw <n8_shaw@y...>
• Subject: Re: OT: Schemas and entities
• From: "J.Pietschmann" <j3322ptm@y...>
• Date: Mon, 12 May 2003 22:24:52 +0200
• Cc: xml-dev@l...
• In-reply-to: <20030512180341.64469.qmail@w...>
• References: <20030512180341.64469.qmail@w...>
• User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.3) Gecko/20030312

Nathan Shaw wrote:
> I am working on converting our DTDs to W3C Schemas. I
> have read quite a bit about how entities are not
> supported by schemas, but I am still a bit confused by
> it. I understand that character replacement entities
> that have to be defined in the DTD (such as nbsp;,
> amp;, etc...) are not supported, but if I use an ASCII
> numerical replacement entity (such as 160;, 38;,
> etc...) is that ok? Do numerical entities such as
> those work in both elements and attributes with
> schemas?

The things you call "numerical entities" are called "character
references" in the spec
   http://www.w3.org/TR/REC-xml#dt-charref
These are used for putting arbitrary Unicode characters into
documents regardless whether they can be expressed in the document
encoding or not.
There is no such a thing as "character replacement entities",
although an entity may be defined as a single character. This
is nothing more than a special case.
Entities must be declared in DTDs, according to the spec, with the
exception of a few predefined entities:
    http://www.w3.org/TR/REC-xml#sec-predefined-ent

If you don't use a DTD, you can't use any entity other than
the predefined entities, but you can use character references
without restriction (becuase they don't need a definition).
This is regardless whether you use a schema or not.

HTH
J.Pietschmann

• References:
  • OT: Schemas and entities
    • From: Nathan Shaw <n8_shaw@y...>

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