Re: Optional features considered harmful
On Thu, 24 Oct 1996 21:32:46 +0000, James Clark <email@example.com> wrote:
>At 15:23 24/10/96 CDT, Michael Sperberg-McQueen wrote:
>>>It would be easier to make this work if we disallowed references to
>>>external text entities in attribute values, but hopefully people can
>>>live without those.
>>Er, I'm sorry if I'm missing something, but doesn't clause 184.108.40.206
>>(p. 335 of Handbook) restrict ENTITY/ENTITIES attributes to
>>data and SUBDOC entities? I.e. isn't your conditional already met?
>I'm talking about *references*; for example,
> <!entity e system "e.sgm">
> <foo a1="&e;">
Maybe that's the problem.
In order for an external SGML entity to be ignored safely by the parser, it has
to be a document entity (or subdoc, which for our purposes is the same thing).
Therefore, if we restrict external SGML/XML entities to being referenced from
attribute values, we can have reusable objects (as Eliot has pointed out) and we
don't have to redefine the meaning of an entity reference.
<p>As is shown in the following text:<quoteref entity=ent1> ...</p>
Of course, "quoteref" is really a typed hyperlink, as is any "entity reference"
that a parser can safely ignore.
My conclusion: drop the optional entity references. We'll get them back in a
robust and fully conforming form when we add hyperlinking.
Charles F. Goldfarb * Information Management Consulting * +1(408)867-5553
13075 Paramount Drive * Saratoga CA 95070 * USA
International Standards Editor * ISO 8879 SGML * ISO/IEC 10744 HyTime
Prentice-Hall Series Editor * CFG Series on Open Information Management