4682 2007-06-21 15:59:30 +0000 Attribute based reference schemes 2007-09-19 23:21:03 +0000 1 1 1 Unclassified SML Core unspecified PC Windows XP RESOLVED FIXED P2 normal Second draft 1 sandygao kumarp public-sml oldest_to_newest 15496 0 sandygao 2007-06-21 15:59:30 +0000 Should SML allow attribute based reference schemes? SML currently uses xsi:nil="true" as an indication for "this reference has no value". In XML Schema, xsi:nil only controls whether an element has any child content, and does *not* control whether the element carries attributes or not. As a consequence, if a reference schema uses attributes, e.g. <my:myRefElement sml:ref="true" my:reference="location" xsi:nil="true"/> then the xsi:nil based approach to determine whether a reference is nil is not reliable. We need to decide whether we want to support attribute based schemes. If we do, we can't rely on xsi:nil for nil references. whether we should require reference pointers be children. 16122 1 kumarp 2007-08-10 00:20:10 +0000 Refer to the following related bug: 4884 update the definition of a null reference to include the unimplemented-schemes case If we update the definition of a null ref as described in the bug, we no longer need to rely on xsi:nil value to define null ref. Consequently, the issue mentioned in this bug goes away. 16417 2 pratul.dublish 2007-09-07 03:52:12 +0000 I think that the bug description is a bit confusing since it mixes the issues of supporting attribute-based reference schemes and identification of null references. The introduction of sml:nilref solves the latter issue, but the issue of attribute-based schemes still remains. 16531 3 johnarwe 2007-09-13 18:42:14 +0000 Consensus 2007-09-13 telecon: 4884 handles null ref portion of this bugzilla. Consensus 2007-09-13 telecon: attribute based ref schemes are allowed in SML. If we find anything in the spec that doesn't work well with attribute-based reference schemes, it is grounds for raising an issue. 16552 4 kumarp 2007-09-14 06:43:16 +0000 added text: A reference scheme MAY use elements, attributes or both to capture the information necessary to identify a resource. 16693 5 sandygao 2007-09-19 17:34:38 +0000 The change mentioned in comment #4 answer the immediate question about schemes that use attributes, but the new text is assuming that schemes will always uses some elements or attribute, which as far as I know has not been adopted as a requirement for defining a scheme. One example we discussed before is a scheme that always resolves to the root element of the current document, where it doesn't depend on either elements or attributes. And a scheme may want to define its behavior in terms of a processing instruction, which would seem to be a perfectly valid scheme. Suggest to use something similar to: "A reference scheme normally uses, but is not required to use, child elements, attributes or both to capture ..." 16698 6 kumarp 2007-09-19 23:20:19 +0000 changed the text as suggested by Sandy: A reference scheme normally uses, but is not required to use, child elements, attributes or both to capture the information necessary to identify a resource.