Re: XML FAQ: some questions
On Tue, 18 Feb 1997 10:09:27 -0500 Peter Flynn said:
>A couple of unanswered questions that I'd like to pre-empt:
>BTW is there a more recent spec that 961114? I trawled the logs
>but I couldn't see a reference.
Not yet. Soon, we hope.
>1. What *may*, and what *must* precede the root element in a
> well-formed XML document? The spec isn't very clear
> on which PIs are compulsory and which are optional.
I read productions 27-31 as meaning:
- the root element must be preceded by a prolog
- the prolog must begin with an XML declaration
i.e. <?XML version='1.0' ... ?>
- the prolog may contain PIs, comments, one document type
declaration, and white space, following the XML declaration
Which part of this isn't clear from the spec?
>2. How may entities be used in XML? ie whether general
> entities can be included and to what depth.
Yes, general entities may be used. No depth restriction is made.
>3. The restriction in WF documents on what elements may occur
> within what others is not clear (3.2):
> As a consequence of this, for each non-root element C,
> there is one other element P such that C is in the content of P,
> but is not in the content of any other element
> that is in the content of P.
> Then P is referred to as the parent of C, and C as the child of P.
> Here's a non-root element C which we call PARA in some DTD or other.
> There is _an_other element (not _one_ other) P which we call SECT.
> PARA is in the content of SECT. So far so good.
> But SECT has in its content also an element called NOTE.
> NOTE has PARA in its content model.
The paragraph quoted is referring to the elements (instances), not
to their types; to actual containment, not potential containment.
A PARA contained directly within a NOTE has exactly one parent element:
the NOTE. The fact that other PARA elements have or can have
parents with GIs other than NOTE does nothing to change the
nature of the parent-child relationship.
-C. M. Sperberg-McQueen
ACH / ACL / ALLC Text Encoding Initiative
University of Illinois at Chicago