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[Bug 17474] New: Annotation Assertions

From: <bugzilla@jessica.w3.org>
Date: Tue, 12 Jun 2012 17:39:06 +0000
To: public-qt-comments@w3.org
Message-ID: <bug-17474-523@http.www.w3.org/Bugs/Public/>

           Summary: Annotation Assertions
           Product: XPath / XQuery / XSLT
           Version: Last Call drafts
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: XQuery 3.0
        AssignedTo: jonathan.robie@gmail.com
        ReportedBy: mike@saxonica.com
         QAContact: public-qt-comments@w3.org

I was probably not concentrating very well while annotation assertions were
being discussed; I think I assumed that all would become clear when I read the
final spec. In fact, for someone who wasn't listening to the debates at the
time, the spec is as clear as mud.

Let's start with the definition:

[Definition: If an annotation is present in a FunctionTest, it is called an
annotation assertion.]

Well, for a start, this is a very odd sort of definition. It's a bit like
saying that if an apple is present in a restaurant it is called a dessert. This
leaves me confused as to whether all apples are desserts or whether all
desserts are apples. It might be better to define the concept syntactically:

[189]       FunctionTest       ::=       AnnotationAssertion* (AnyFunctionTest
| TypedFunctionTest)

[189a] AnnotationAssertion ::= Annotation

Here it's no longer true that an AnnotationAssertion IS an annotation, it just
takes the same syntactic form as an annotation.

The next thing we read is "Annotation assertions further restrict the set of
functions that are matched by a FunctionTest." So, I want to know how. I know
that %speed:fast is an annotation, so I might conclude that it is also an
annotation assertion, and with some imagination I might conclude that a
FunctionTest carrying this assertion will only match functions with this
annotation. But the spec doesn't actually say that. Perhaps (my imagination is
now going wild, there is nothing in the spec to say otherwise) the annotation
assertion %speed:fast will also match a function annotated as %speed:superfast.
If that's a possibility, I think the spec should say so. There certainly needs
to be something to describe the relationship between annotation assertions and

Read on, Macduff. "Implementations MAY define further annotation assertions,
whose behaviour is implementation-defined." What does "further" mean? Does it
mean assertions that don't take the syntactic form of an annotation? I suspect
not. I suspect it means annotation assertions that are not defined in this
spec. The set of annotation assertions defined in this spec appears to be
empty, is that right? So "further" is a bit of a euphemism. ("Behaviour",
incidentally, needs to be spelt the American way).

Moving on: "Implementations MAY provide a way for users to create their own
annotation assertions.". So my assumption that you create an annotation
assertion merely by using an annotation within a FunctionTest is clearly wrong.
That's what the definition implied, but it seems that not every apple found
within a restaurant is ipso facto a dessert. This is confirmed by the first
Note: "There are no annotation assertions that correspond to the %public and
%private annotations."  So I'm coming to the conclusion that the only
assertions that can be used as annotation assertions are those that are
explicitly licensed to be used in that way by some mechanism outside this
specification. Which presumably means there is some error condition that needs
to be added to the spec to disallow others. (Or perhaps it isn't an error,
perhaps they are just ignored? In which case we need to be clear about whether
an annotation assertion that's ignored is or is not an annotation assertion).

We're getting close to the end "Other specifications in the XQuery family also
use annotation assertions.". Perhaps, I'm feeling, the "also" is redundant?
Perhaps what has happened is that XQuery itself doesn't use them at all, but
they are available for use by other specifications? If so, that's what we
should say.

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Received on Tuesday, 12 June 2012 17:39:08 UTC

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