Allow IRIs for XML namespaces

XML allows IRIs for namespaces, and compares them without any
encoding or decoding.  This means that our requirement that
namespaces are URIs will cause comparisons with other tools that
use IRIs (without mapping them down to URIs) to fail.

This change relaxes the description and allows the use of
unencoded IRIs.

Author: handrews

src/oas.md

@@ -3968,7 +3968,7 @@ See examples for expected behavior.
 | Field Name | Type | Description |
 | ---- | :----: | ---- |
 | <a name="xml-name"></a>name | `string` | Replaces the name of the element/attribute used for the described schema property. When defined within `items`, it will affect the name of the individual XML elements within the list. When defined alongside `type` being `"array"` (outside the `items`), it will affect the wrapping element if and only if `wrapped` is `true`. If `wrapped` is `false`, it will be ignored. |
-| <a name="xml-namespace"></a>namespace | `string` | The URI of the namespace definition. Value MUST be in the form of a non-relative URI. |
+| <a name="xml-namespace"></a>namespace | `string` | The IRI ([[RFC3987]]) of the namespace definition. Value MUST be in the form of a non-relative IRI. |
 | <a name="xml-prefix"></a>prefix | `string` | The prefix to be used for the [name](#xml-name). |
 | <a name="xml-attribute"></a>attribute | `boolean` | Declares whether the property definition translates to an attribute instead of an element. Default value is `false`. |
 | <a name="xml-wrapped"></a>wrapped | `boolean` | MAY be used only for an array definition. Signifies whether the array is wrapped (for example, `<books><book/><book/></books>`) or unwrapped (`<book/><book/>`). Default value is `false`. The definition takes effect only when defined alongside `type` being `"array"` (outside the `items`). |
@@ -3977,9 +3977,8 @@ This object MAY be extended with [Specification Extensions](#specification-exten
 
 The `namespace` field is intended to match the syntax of [XML namespaces](https://www.w3.org/TR/xml-names11/), although there are a few caveats:
 
-* Versions 3.1.0, 3.0.3, and earlier of this specification erroneously used the term "absolute URI" instead of "non-relative URI", so authors using namespaces that include a fragment should check tooling support carefully.
-* XML allows but discourages relative URI-references, while this specification outright forbids them.
-* XML 1.1 allows IRIs ([RFC3987](https://datatracker.ietf.org/doc/html/rfc3987)) as namespaces, and specifies that namespaces are compared without any encoding or decoding, which means that IRIs encoded to meet this specification's URI syntax requirement cannot be compared to IRIs as-is.
+* Versions 3.1.0, 3.0.3, and earlier of this specification erroneously used the term "absolute URI" instead of "non-relative URI" ("non-relative IRI" as of OAS v3.2.0), so authors using namespaces that include a fragment should check tooling support carefully.
+* XML allows but discourages relative IRI-references, while this specification outright forbids them.
 
 ##### XML Object Examples
 

src/schemas/validation/meta.yaml

@@ -60,7 +60,7 @@ $defs:
       name:
         type: string
       namespace:
-        format: uri
+        format: iri
         type: string
       prefix:
         type: string