XML resource identifiers

/ François Yergeau <francois@yergeau.com> was heard to say:
| Here goes:
|
| ===========================================================
| XML 1.0, 4.2.2
| [http://www.w3.org/TR/2004/REC-xml-20040204/#sec-external-ent]
| XML 1.1, 4.2.2
| [http://www.w3.org/TR/2004/REC-xml11-20040204/#sec-external-ent]
| ===========================================================
|
| System identifiers (and other XML strings meant to be used as URI
| references)
|
| [Definition: *XML resource identifiers* are XML string meant to be
| used as IRI references or URI references].

I changed that definition to be singular instead of plural.

| System identifers are XML resource identifiers.

I'm going to omit this sentence while the section is in XLink 1.1. I
think it's likely to cause confusion in that context (though it'll
have no negative impact when we change XLink to point to XML 4th ed.

| An XML resource identifier may contain
| characters that, according to [IETF RFC 3897] and [IETF RFC 3986],
| must be escaped before the string can be used to retrieve the

RFC 2119 MUST?

| referenced resource. To convert an XML resource identifier to an IRI
| reference, the following characters must be escaped:
|
|      * the control characters #x0 to #x1F and #x7F (most of which
| cannot appear in XML)
|      * space #x20
|
|        Note:
|
|        Authors are advised to avoid unescaped spaces, as XML Schema
| has identified them as an interoperability risk.
|
|      * the delimiters < #x3C, > #x3E and " #x22
|      * the unwise characters { #x7B, } #x7D, | #x7C, \ #x5C, ^ #x5E
| and ` #x60
|
| These characters are escaped by applying to them steps 2.1 to 2.3 of
| Section 3.1 of [IETF RFC 3987].
|
| If necessary for the implementation, an IRI reference is converted to
| a URI reference by following the prescriptions of Section 3.1 of [IETF
| RFC 3987]. This conversion MUST be performed only when absolutely
| necessary and as late as possible in a processing chain. In
| particular, neither the process of converting a relative IRI to an
| absolute one nor the process of passing a IRI reference to a process
| or software component responsible for dereferencing it SHOULD trigger
| escaping.

                                        Be seeing you,
                                          norm

-- 
Norman.Walsh@Sun.COM / XML Standards Architect / Sun Microsystems, Inc.
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