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RE: XML Schema WG comments on Functions and Operators

From: Ashok Malhotra <ashokma@microsoft.com>
Date: Tue, 26 Aug 2003 04:53:24 -0700
Message-ID: <E5B814702B65CB4DA51644580E4853FB0A5ED7CF@red-msg-12.redmond.corp.microsoft.com>
To: "C. M. Sperberg-McQueen" <cmsmcq@acm.org>, <public-qt-comments@w3.org>
Cc: "W3C XML Schema IG" <w3c-xml-schema-ig@w3.org>

Dear Michael and the XML Schema WG.
Great comments!  I have responded to some by clarifying wording and others by creating issues for the XML Query WG or the F&O taskforce to discuss.
On two issues I have started discussion threads.

This is not a formal response from the Query WG.  Feel free to comment
if you think something has not been addressed adequately.

All the best, Ashok

> -----Original Message-----
> From: public-qt-comments-request@w3.org [mailto:public-qt-comments-
> request@w3.org] On Behalf Of C. M. Sperberg-McQueen
> Sent: Friday, August 01, 2003 7:55 PM
> To: public-qt-comments@w3.org
> Cc: W3C XML Schema IG
> Subject: XML Schema WG comments on Functions and Operators
> 
> 
> Dear colleagues:
> 
> The XML Schema Working Group congratulates the XML Query and XSL
> Working Groups on their progress, and in particular on the Last Call
> draft of "XQuery 1.0 and XPath 2.0 Functions and Operators".
> 
> We have not been able to review the last call draft in as much detail
> as we would have liked, but for what they are worth our comments are at
> http://www.w3.org/XML/Group/2003/07/xmlschema-fo-comments.html (an
> ASCII version is reproduced below for the convenience of those with
> access to their email but not to the Web).
> 
> We apologize for the tardy arrival of these notes.
> 
> -C. M. Sperberg-McQueen, for the W3C XML Schema WG
> 
> ................................................................
> 
> 
>     [1]W3C [2]Architecture Domain [3]XML | [4]XML Schema | [5]Member
>     Events | [6]Member-Confidential!
> 
> W3C XML Schema WG
> 
> Notes on XQuery 1.0 and XPath 2.0 Functions and Operators
> 
> 1 August 2003
>       _________________________________________________________________
> 
>       * 1. [7]Schema-related issues
>            + 1.1. [8]Alignment of date/time values
>            + 1.2. [9]The type anyAtomicType
>            + 1.3. [10]The type untypedAtomic
>            + 1.4. [11]Alignment on strings and URIs
>            + 1.5. [12]Whitespace handling and lexical forms
>            + 1.6. [13]Negative zero
>            + 1.7. [14]Totally ordered Booleans
>       * 2. [15]Other technical issues
>            + 2.1. [16]The fn:base-uri property
>            + 2.2. [17]Alignment of references
>            + 2.3. [18]Characters and collation units
>            + 2.4. [19]Surrogate pairs and Unicode scalar values
>            + 2.5. [20]Definition of whitespace
>            + 2.6. [21]Required normalization functionality
>            + 2.7. [22]Case folding
>            + 2.8. [23]Escaping URIs
>            + 2.9. [24]The binary types
>            + 2.10. [25]Minor items
>                 o 2.10.1. [26]User control of collations
>                 o 2.10.2. [27]Section 7.3.1.1 Examples
>       * 3. [28]Editorial notes
>       _________________________________________________________________
> 
>     This document contains comments on the Last Call draft of 2 May 2003
>     of XQuery 1.0 and XPath 2.0 Functions and Operators transmitted to the
>     XML Query and XSL Working Groups on behalf of the XML Schema Working
>     Group. These draft comments have not been reviewed by the XML Schema
>     Working Group and do not necessarily command consensus within the
>     group; because we will not meet again until 28 August, the Working
>     Group directed at its meeting today that these notes should be
>     transmitted to the XML Query and XSL Working Groups without awaiting
>     review.
>     In addition to the comments below, please note that several of the
>     [29]general comments sent on 14 July relate to the functions and
>     operators and data model specifications. Some of those comments sent
>     earlier overlap with some comments below.
> 
> 1. Schema-related issues
> 
>     The comments in this section relate to the use of XML Schema in the
>     F/O specification and thus to the particular area of responsibility
>     borne by the XML Schema WG.
> 
> 1.1. Alignment of date/time values
> 
>     The provision for preserving timezone information in the values of
>     xs:dateTime, xs:date, and xs:time continues to concern us. We believe
>     that a discrepancy of this kind between F/O and XML Schema will hurt
>     users and impede uptake of both specifications.
> 
>     We believe F/O and XML Schema need to align on this, either by F/O
>     changing to the XML Schema value space, or by changing the value space
>     as part of XML Schema 1.1, or by some other mutually agreed upon
>     solution.
[AM] Ongoing XPath/XQuery issue SC1: http://lists.w3.org/Archives/Member/w3c-xml-query-wg/2003Jul/0130.html
> 
> 1.2. The type anyAtomicType
> 
>     We reiterate our concern over the introduction of anyAtomicType into
>     the type hierarchy. We believe that a discrepancy of this kind between
>     F/O and XML Schema will hurt users and impede uptake of both
>     specifications.
> 
>     We believe F/O and XML Schema need to align on this, either by F/O
>     aligning with XML Schema 1.0 or by XML Schema 1.1 aligning with F/O.
[AM] Ongoing XPath/XQuery issue SC2: http://lists.w3.org/Archives/Member/w3c-xml-query-wg/2003Jul/0132.html
> 
> 1.3. The type untypedAtomic
> 
>     We reiterate our concern over the introduction of untypedAtomic into
>     the type hierarchy. As with the other discrepancies, we believe
>     alignment of the QT specs and XML Schema is critically important.
>     Section 1.3.2 says xdt:untypedAtomic is used wherever the PSVI has
>     xs:anySimpleType; please note that in the PSVI, this will be the case
> 
>       * when the element or attribute in question was declared as having
>         type anySimpleType
>       * when the attribute in question had no declaration and the schema
>         processor assumed the simple urtype for it in the course of lax
>         validation or error recovery
> 
>     Note that elements will not be assigned the anySimpleType as their
>     type property in the course of lax validation or error recovery; they
>     will have xs:anyType instead. Your use of xdt:untypedAtomic for
>     xs:anySimpleType but not for elements which (a) lack child elements
>     and (b) are assigned to xs:anyType may lead to results which puzzle
>     some of your users; we believe you may wish to consider changing your
>     mapping rules to assign xsd:untypedAtomic to such elements.
[AM] Ongoing XPath/XQuery issue SC3: http://lists.w3.org/Archives/Member/w3c-xml-query-wg/2003Jul/0133.html
> 
> 1.4. Alignment on strings and URIs
> 
>     The table at the beginning of section 2, Accessors, shows functions
>     which are intended (judging by their names) to return URIs and which
>     return values of type xs:string instead of xs:anyURI. Similarly,
>     various functions which accept URIs as arguments are given signatures
>     using xs:string as the type, which in turn necessitates ad hoc rules
>     of the form "If $collationLiteral is not in the lexical space of
>     xs:anyURI, an error is raised".
> 
>     As you know from our inquiry to you in mid-July, it has been suggested
>     that in XML Schema 1.1 the xs:anyURI type be made a restriction of
>     xs:string. But for now, there appears to be a discrepancy between the
>     use of strings to represent URIs here and the provision of a distinct
>     (and, for typing purposes, disjoint) type in XML Schema 1.0.
>     We need to align on this.
[AM] Ongoing XPath/XQury discussion started by Jim Melton's note:
http://lists.w3.org/Archives/Member/w3c-xml-query-wg/2003Jul/0165.html
> 1.5. Whitespace handling and lexical forms
> 
>     In section 5.1, paragraph 4 reads in part: "If the argument to a
>     constructor function is a string literal, the literal must be a valid
>     lexical form for its type ... Whitespace normalization is applied
>     before validation ..."
> 
>     In all the cases which immediately come to mind, if the argument is a
>     valid lexical form for a type, there is no need to perform any
>     whitespace normalization on it. In XML Schema, it is the result of
>     whitespace normalization, not the input to it, which must be a legal
>     lexical form; we believe readers will be less confused if your usage
>     of the terms and ours is consistent.
> 
>     A possible rewording: "If the argument to a constructor function is a
>     string literal, then whitespace normalization is applied as indicated
>     by the whitespace facet for the datatype. The whitespace-normalized
>     string must be a valid lexical form for the type, as specified ..."
[AM]  That's just sloppy wording.  Fixed!  Thanks!
> 
> 1.6. Negative zero
> 
>     In section 6, a note explains that the value space of xs:float and
>     xs:double has been extended vis-à-vis that given by XML Schema, to
>     include a negative zero. The note also explains that the negative zero
>     will "never be obtained from the typed value of a node."
> 
>     We believe this discrepancy is untenable, and we are not clear why it
>     has proven necessary to introduce it.
> 
>     As far as we can tell by examining the specification, the spec
>     mentions different treatment for positive and negative zero only for
>     the functions described in section 6.4 (fn:floor, fn:ceiling,
>     fn:round, and fn:round-half-to-even): in the description of each of
>     these functions it is noted that if a zero is given to the function as
>     an argument, the sign of the zero returned as the value of the
>     function is the same as the sign of the zero passed in as an argument.
>     (The discussion of fn:ceiling mentions other cases when negative zero
>     is returned; the discussion of fn:floor passes over the analogous
>     cases in silence.) Other mentions of the signed zeroes in this
>     specification invariably specify either that something is true both
>     for positive and for negative zero or else that a constructor may
>     return either a positive or a negative zero.
> 
>     Could you explain the motive for introducing this discrepancy with the
>     value space defined in XML Schema? Would it not suffice to observe
>     that IEEE 754 has both positive and negative zeroes, which are treated
>     as different machine representations of the same values in the
>     xs:float and xs:double value spaces, and (optionally) that the prose
>     occasionally mentions these distinct representations of zero in the
>     interests of alignment with IEEE 754, even though formally they are
>     the same value?
> 
>     Is it essential to introduce an incompatibility with XML Schema here
>     instead of treating positive and negative zeroes as one value with two
>     machine representations?
[AM] Changed wording appropriately.
> 
> 1.7. Totally ordered Booleans
> 
>     We do not believe that it makes sense to impose a user-visible
>     ordering on the Boolean data type. Can you explain the rationale?
>     This is a discrepancy between F/O and XML Schema which must, we
>     believe, be aligned.
[AM] Created issue.
> 
> 2. Other technical issues
> 
>     The comments in this section relate to technical issues other than the
>     use of XML Schema in the F/O specification; the XML Schema WG claims
>     no particular responsibility or expertise on these questions but
>     raises them because they seem to need attention.
> 
> 2.1. The fn:base-uri property
> 
>     In section 2.5, the first paragraph defines a base-uri property for
>     all node types: "Document, element and processing-instruction nodes
>     have a base-uri property.... The base-uri of all other node types is
>     the empty sequence."
> 
>     The next paragraph begins by explaining what happens "If the accessor
>     is called on a node that does not have a base-uri property ..." If all
>     nodes have the property, how can such a node exist?
> 
[AM] Fixed wording.  Wording needs to be fixed in the datamodel document also.  Norm has promised to fix.
> 2.2. Alignment of references
> 
>     XML Schema and the Functions and Operators spec should refer to the
>     same version of Unicode. At the moment, this appears not to be true.
[AM] No disagreement in principle but I'm not sure how to operationalize.  The Schema Primer and Part 1 have no references to Unicode.  Part 2 contains a normative reference to the Unicode Character Database and a non-normative reference to (an outdated version) of the Character Model.  The F&O refers to Version 2 of the Unicode Standard (should we change to version 4.0?), the Unicode Case Mappings Report, the Unicode Collation Algorithm and the 2002 version of the Character Mapping draft.  It seems that the Schema 2nd edition should align with the F&O!
> 
> 2.3. Characters and collation units
> 
>     The discussion of collation units in the second note of section 7.3
>     says that collation decomposes a string "into a sequence of units,
>     each unit consisting of one or more characters", and that various
>     comparison operations are performed on these units. The functions
>     fn:starts-with, fn:ends-with, fn:substring-before, and
>     fn:substring-after are all mentioned as operating on such a segmented
>     string.
> 
>     The list of functions at the beginning of section 7.4, however,
>     describes them as operating on characters, not on the nameless
>     collation units consisting of one or more characters each. This looks
>     like a contradiction.
> 
>     We believe that the general level of confusion is best minimized, and
>     the world becomes a better place, if in XML-related specifications the
>     word character is used always and only for the units of the Universal
>     Character Set defined by Unicode and by ISO 10646. The word should not
>     be used (however great the temptation becomes at times) to denote the
>     culturally specific units of writing systems (e.g. letters, symbols,
>     signs, graphemes, or what have you).
> 
>     We suggest recasting the descriptions in 7.4 to describe the effect of
>     the functions in terms of the collation units, rather than in terms of
>     characters. In order to avoid repeating the phrase "the nameless units
>     of one or more characters into which a collation segments a string for
>     purposes of comparison", you may wish to define the term letter,
>     grapheme, collation unit, or thingy with that meaning.
[AM] Created issue.  
> 
> 2.4. Surrogate pairs and Unicode scalar values
> 
>     Section 7.4.6 (like some others) has a note calling attention to the
>     fact that some implementations will represent characters with code
>     points higher than xFFFF by using surrogate pairs. You quite correctly
>     avoid using the term code point for the things which make up the
>     surrogate pair, since in section 7.1 you have defined code point as
>     excluding surrogates. But the term 16-bit values is not defined, as
>     far as we can tell.
> 
>     Also, in Unicode 2 and 3 there are (as far as we have been able to
>     tell) no rules that forbid a double encoding of characters outside the
>     Basic Multilingual Plane (i.e. first representing them within the BMP
>     as surrogate pairs, and then encoding the sequence of BMP items in
>     UTF-8). Even if it is discouraged (and it is indeed outlawed in
>     Unicode 4.0), surrogate pairs might well show up not only in UTF-16
>     but also in UTF-8, where they will presumably be presented by
>     Unicode-oblivious character libraries not as pairs of 16-bit values
>     but as four-octet sequences whose intepretation in terms of Unicode
>     scalar values requires slightly special rules.
> 
>     Note that the definition of code points given in section 7.1 agrees
>     with the definition of Unicode scalar values in Unicode 4.0 in
>     excluding the surrogate range, but not with Unicode 2.0 (the version
>     cited in your normative references), or Unicode 3, which define a
>     Unicode scalar value as "a number N from 0 to 10FFF[16]", without
>     leaving any gap for the surrogates.
[AM] Started discussion on how to respond.  
> 
> 2.5. Definition of whitespace
> 
>     Section 7.4.10 defines the function fn:normalize-space as doing
>     various things to whitespace, but it does not define the term
>     whitespace. It should, since various definitions are possible.
>     The Unicode character database, for example, lists the following
>     Unicode characters as whitespace in the file PropList-3_1_0.txt:
> 
>       * 0009..000D ; White_space # Cc [5] <control>..<control>
>       * 0020 ; White_space # Zs SPACE
>       * 0085 ; White_space # Cc <control>
>       * 00A0 ; White_space # Zs NO-BREAK SPACE
>       * 1680 ; White_space # Zs OGHAM SPACE MARK
>       * 2000..200A ; White_space # Zs [11] EN QUAD..HAIR SPACE
>       * 2028 ; White_space # Zl LINE SEPARATOR
>       * 2029 ; White_space # Zp PARAGRAPH SEPARATOR
>       * 202F ; White_space # Zs NARROW NO-BREAK SPACE
>       * 3000 ; White_space # Zs IDEOGRAPHIC SPACE
> 
>     The XML specification defines a smaller set of characters as
>     whitespace, for purposes of whitespace normalization.
> 
>     So some definition is definitely needed.
> 
[AM] Done!
> 2.6. Required normalization functionality
> 
>     Section 7.4.11 requires conforming implementations to support Unicode
>     normalization form NFC.
> 
>     Why is normalization form W3C not also required?
[AM] Created issue.
> 
> 2.7. Case folding
> 
>     Sections 7.4.12 and 7.4.13 define functions for case folding.
>     Since case folding is not consistent across languages and locales, we
>     have grave doubts about the wisdom of this inclusion, and some members
>     of the WG would advise you to drop these functions, which are not and
>     cannot be language- and culture-neutral.
> 
>     There is precedent: the decision to drop case-folding of names from
>     the design of XML resulted from the realization that every
>     case-folding algorithm available, including the use of the Unicode
>     case mapping tables, has an inherent cultural bias. The inclusion of
>     culturally and linguistically biased functions does not contribute to
>     achieving the goal of universal accessibility for the Web. Some
>     members of the XML Schema WG believe your spec should not go forward
>     with these functions in it.
> 
>     If you retain these functions, you should at the very least warn users
>     that
> 
>       * Results may violate user expectations (in Québec, for example, the
>         standard uppercase equivalent of "é" is "É", while in metropolitan
>         France it is more commonly "E"; only one of these is supported by
>         the function as defined).
>       * Many characters of class Ll lack uppercase equivalents in the
>         Unicode case mapping tables (we stopped counting at 150 or so);
>         many characters of class Lu lack lowercase equivalents.
>       * The two functions are not inverses of each other, so that for a
>         string S of upper-case characters, fn:upper-case(fn:lower-case(S))
>         is not guaranteed to return S, nor is
>         fn:lower-case(fn:upper-case(S)) for a string S of lower-case
>         characters. Latin small letter dotless i (as used in Turkish) is
>         perhaps the most prominent lower-case letter which will not
>         round-trip, as Latin capital letter i with dot above is the most
>         prominent upper-case letter which will not round trip; there are
>         others.
> 
>     You may also wish to make the case mapping depend on the default or a
>     user-specified collation.
> 
[AM] Created issue.
> 2.8. Escaping URIs
> 
>     The rules for escaping URIs should be aligned across all W3C
>     specifications; otherwise, we will drive our users crazy.
> 
>     We think that means that you should reference and implement the
>     algorithm specified in the XML Linking specification
>     ([30]http://www.w3.org/TR/2001/REC-xlink-20010627/#link-locators) and
>     referenced by XML Schema, or the algorithm given in the W3C Character
>     Model specification (which was the same algorithm the last time we
>     looked).
> 
>     In particular, some members of the XML Schema WG were surprised to see
>     that your algorithm escapes the percent sign in some cases but not
>     others; this does not seem to be a feature of the algorithm given by
>     XML Linking and by the Character Model.
[AM] Created issue.
> 
>     That said, we believe that you do your readers a good service by
>     listing explicitly the affected characters. By suggesting that you
>     refer to the Linking/CharMod algorithm, we do not mean to suggest that
>     you should make your spec less useful by omitting these lists.
>     (Editorial note: it would perhaps be useful to some readers to have a
>     brief discussion of why the advice given in the last paragraph should
>     be followed; our readers did not understand the rationale for this
>     advice.)
> 
> 2.9. The binary types
> 
>     Section 12.1.1 says that op:hexBinary-equal returns true if its
>     arguments "are of the same length and contain the same code-points";
>     similarly in 12.1.2 for op:base64Binary-equal.
> 
>     The term code-point was defined in section 7.1 as denoting integers
>     between 0 and 1114111 (x10FFFF), with a gap in the range where Unicode
>     surrogates occur. It seems to be used here to denote what other
>     specifications refer to as octets (bit strings of length 8).
> 
>     Taking the term code point in the sense of `octet', the definition
>     still does not match our intuitions of what an equality test on binary
>     data must do: it is not enough that each argument contain the same
>     octets; they must contain them in the same order.
> 
>     Suggested rewording: "are identical strings of octets". If you wish to
>     avoid the word octet, "are identical bit strings" might do, although
>     it omits the relatively important fact that the values in question
>     must have 8×n bits for some integer n.
[AM] Wording fixed.  Thanks!
> 
> 2.10. Minor items
> 
> 2.10.1. User control of collations
> 
>     Section 7.3 says in part "This specification does not use xml:lang to
>     identify the default collation, in part because collations should be
>     determined by the user of the data, not (normally) the data itself,
>     and because ..."
> 
>     The second reason given is sound. The first (collations should not
>     normally be determined by the data) is often advanced as a principle,
>     but does not seem to all members of the XML Schema WG to be
>     universally true. We are thus grateful for the "(normally)" in the
>     sentence. But in any case, the first reason given here leads to a
>     non-sequitur: it would be a reason not to make xml:lang determine the
>     collation sequence without possibility of user override. But it does
>     not, even on its face, provide a reason not to use xml:lang to
>     identify the default collation. We suggest dropping the first reason;
>     the second suffices.
[AM] Done!  Thanks!
> 
> 2.10.2. Section 7.3.1.1 Examples
> 
>     The fourth example in section 7.3.1.1 says that
> 
>        fn:compare('Strassen', 'Straße')
> 
>     "returns 1 if and only if the default collation includes provisions
>     that equate `ss' and the (German) character `ß' (`sharp-s')." Unless
>     we have misunderstood the definition of the function, the return value
>     should also be 1 if the default collation sorts "ß" (sharp s) before
>     "s". Deleting the phrase "and only if" would remove the error.
> 
[AM] Done!  Thanks!
> 3. Editorial notes
> 
>     In the course of our work, some editorial points were noted; we list
>     them here for the use of the editors. We do not particularly expect
>     formal responses on these comments.
> 
>      1. Definition of must. Section 1.1 defines must thus:
> 
>           Conforming documents and processors are required to behave as
>           described; otherwise, they are non-conformant or in error.
> 
>         Is the "or" inclusive or exclusive, or is "in error" intended as a
>         synonym or approximate synonym for "non-conformant"? Possible
>         alternatives: "otherwise, they are non-conformant and in error",
>         "otherwise, they are either non-conformant or else in error",
>         "otherwise, they are non-conformant, i.e. in error".
[AM] Changed to "either non-conformant or else in error."
> 
>      2. Definition of stable. In section 1.1, the definition of stable
>         says, inter alia:"Some other functions ... have an explicit
>         dependency on the dynamic context". Unless this means that they
>         accept an argument representing the dynamic context, it seems at
>         first glance as if explicit is here used with the meaning
>         `implicit'. Perhaps what is intended is that the documentation
>         will explicitly mention this dependency. Perhaps the best thing to
>         do would be just to drop the explicit; if you really wish to
>         stress the promise of documentation, perhaps read "Some other
>         functions ...have a dependency on the dynamic context ... These
>         functions are said to be contextual. [INS: Contextual functions
>         are always identified as such in their descriptions. :INS] "
[AM] Fixed!
> 
>      3. The term back up. The phrase back up appears to be used several
>         times as a technical term (e.g. last paragraph of 1.7). What does
>         it mean?
[AM]  Sloppy wording.  Used to indicate that the op: functions describe the semantics of the operators in the language.  Changed wording.
> 
>      4. The term QName. Some readers (including some members of the XML
>         Schema WG) are likely to find it disorienting for the term QName
>         to be used here as a synonym for expanded name or universal name,
>         and not with the same meaning QName has in the XML Namespaces
>         Recommendation. We recognize, however, that what is returned is
>         precisely a member of what XML Schema 1.0 defines as the value
>         space of the xs:QName type, so that the use of the term xs:QName
>         to denote (for example) the return type of the accessor
>         fn:node-name is not only unexceptionable but necessary for
>         consistency. We don't have a good solution for you here; we only
>         note the difficulty. Perhaps a note calling the reader's attention
>         to the issue would be in order (similar to the note on this topic
>         in the Data Model spec).
> 
>         Some members of the WG suggest that this spec, like the Data
>         Model, should prefer the term expanded QName where possible, to
>         stress that what is referred to is the pair in the value space,
>         not the colonized Name in the lexical space.
[AM] Added note.  Will check carefully that expanded-QName is used where needed.
> 
>      5. No parameters and the empty list of parameters:
> 
>         On first reading, the signatures of fn:string and fn:error suggest
>         an ambiguity to some readers: the call fn:error() appears to match
>         both the first and the second signatures.
> 
>         Members of the WG who have studied XQuery more thoroughly assure
>         the rest of us that there is no ambiguity, so our purpose in
>         making this comment is merely to call your attention to an
>         editorial problem: it might be useful to explain to the reader why
>         the dual signatures showing no arguments and optional arguments
>         are not in fact ambiguous.
[AM] Added a para to clarify using example.
> 
>      6. Section 2.3, first note: the word this seems to need an
>         antecedent; it is not clear to this reader, at least, what that
>         antecedent is. (It's also not clear what problem with blanks in
>         fragment identifiers is being adverted to.)
[AM] Clarified.
> 
>      7. Raising errors: Section 3 para 1 reads in part: "The occurrence of
>         that phrase [sc. `an error is raised'] implicitly causes the
>         invocation of the fn:error function ..." This formulation seems to
>         involve a horrible clash of contexts: the phrase "an error is
>         raised" occurs in this document, and it occurs continuously from
>         the time of publication until the document ceases to exist (if
>         documents can ever cease to exist), while the error, one expects,
>         ought to be raised in a software system which implements the spec,
>         and should probably not be raised continuously from now until the
>         spec ceases to exist, if only because it would make it hard for
>         users to get work done. For the occurrence of a phrase in the spec
>         to cause the raising of an error in conforming software seems to
>         involve a rather unusual kind of action at a distance. To speak a
>         bit more seriously: perhaps the relevant part of the paragraph
>         could be recast, perhaps along these lines: "the phrase `an error
>         is raised' is used to describe the behavior of conforming
>         processors in certain situations. When such situations arise in a
>         running system, a conforming implementation of this specification
>         must invoke the fn:error function defined in this section." This
>         is not perfect, but we hope you get the idea.
[AM] Done!
> 
>      8. Type promotion in multiple or single steps: Section 6.2 says "As
>         far as possible, the promotions should be done in a single step.
>         Specifically, when a decimal is promoted to a double, it must not
>         be converted to a float and then to a double, as this risks loss
>         of precision." [Emphasis added.] These two sentences appear to
>         contradict each other: is the rule about single-step conversions
>         required of conforming implementations ("must"), or recommended
>         without being required ("should")?
[AM} Changed to "should".
> 
>      9. Code points: The note in section 7.1 identifies code points as
>         Unicode scalar values (which are in turn integers), but uses the
>         notation #x0000 and #x10FFFF to refer to the minimum and maximum
>         values. It's not terribly confusing in context, but strictly
>         speaking, this notation is defined in the XML specification as
>         denoting characters, not integers. I believe conventional
>         representations for hexadecimal numbers would write these values
>         as 0, 0H, x0, or 0x, and correspondingly 10FFFFH, x10FFFF, or
>         10FFFFx; there may be other hexadecimal representations you will
>         prefer. The Unicode specification writes 10FFFF[16].
[AM] Changed to "Code points range from x0000 to x10FFFF inclusive, except for the range xD800 to xDFFF inclusive,..."  on your authority.
> 
>     10. v and w: Section 7.3 says "`uve' and `uwe' are considered
>         equivalent in some European languages"; this is unexpected. Are
>         you sure? Which languages?
[AM] Now changed to 'v' and 'w'.  Anders confirms that this is true in Swedish!
> 
>     11. Section 7.4 para 1: for "function" read "functions". Here and
>         elsewhere, we believe that sentences like "Several of these
>         functions use a collation" would do better if "a collation" were
>         replaced with a plural: "Several of these functions use a
>         collation." Unless, of course, all of these functions always use
>         the same collation.
[AM] Typo.  Fixed.
> 
>     12. Section 7.4.6.1, final example: forgive this observation if it's
>         clueless, but since there does not seem to be any addition
>         operator in the example (did we miss it?), it's not immediately
>         obvious what -INF + INF has to do with the interpretation of the
>         example.
[AM] Illustrates XPath 1.0 rule. 
-1 div 0E0.0 => -INF and 1 div 0E0.0 => INF.  Thus, selects characters at positions p where -INF <= p < -INF+INF which is empty since -INF+INF => NaN.
> 
>     13. Section 7.4.15, fn:string-pad: this seems an unfortunate choice of
>         names for a function which does not (despite its name) pad a
>         string with blanks or some other padding character(s), but which
>         simply replicates or copies the string multiple times. Could it be
>         renamed without excessive heartburn?
[AM] We are trying to remove this function and add it to the Appendix on user-defined functions.
> 
>     14. Section 7.4.16, fn:escape-uri: It would help minimize confusion if
>         the lists of characters which are or are not escaped gave the
>         character names as well as the characters themselves in quotation
>         marks. (In the paper copy used by one member of our review task
>         force, this bit of the spec was almost impossible to make out
>         without a magnifying glass.)
[AM] Character names added.  
> 
>     15. Section 7.5.3, fn:replace: The description of the function seemed
>         unclear:
> 
>             The function returns the xs:string that is obtained by
>             replacing all non-overlapping substrings of $input that
>             match the given $pattern with an occurrence of the
>             $replacement string.
> 
>         Replacing all occurrences of the pattern with an occurrence of the
>         replacement string seems to suggest an n for 1 exchange. For "all"
>         read "each".
[AM] Done
 In the following paragraph, one occurrence of $input
>         is not marked as an identifier, one is.
[AM] Done.
> 
> 
> References
> 
>     1. http://www.w3.org/
>     2. http://www.w3.org/Architecture/
>     3. http://www.w3.org/XML/Group
>     4. http://www.w3.org/XML/Group/Schemas
>     5. http://www.w3.org/Member/Eventscal.html
>     6. http://www.w3.org/Member/#confidential
>     7. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e65
>     8. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e70
>     9. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e86
>    10. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e98
>    11. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e145
>    12. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e178
>    13. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e191
>    14. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e238
>    15. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e246
>    16. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e251
>    17. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e278
>    18. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e283
>    19. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e327
>    20. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e350
>    21. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e392
>    22. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e399
>    23. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e444
>    24. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e463
>    25. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e513
>    26. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e516
>    27. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e544
>    28. http://www.w3.org/XML/Group/2003/07/xmlschema-fo-
> comments.html#d0e577
>    29. http://www.w3.org/XML/Group/2003/07/xmlschema-query-notes.html
>    30. http://www.w3.org/TR/2001/REC-xlink-20010627/#link-locators
> 
> 
Received on Tuesday, 26 August 2003 08:28:38 UTC

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