$Id: annotate.xml,v 1.5 2001/08/04 11:19:49 jjc Exp $ JamesClark

jjc@jclark.com

MURATAMakoto

mura034@attglobal.net

4 August 2001 $Id: annotate.xml,v 1.5 2001/08/04 11:19:49 jjc Exp $ 2001OASIS Copyright © The Organization for the Advancement of Structured Information Standards [OASIS] 2001. All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to OASIS, except as needed for the purpose of developing OASIS specifications, in which case the procedures for copyrights defined in the OASIS Intellectual Property Rights document must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by OASIS or its successors or assigns. This document and the information contained herein is provided on an AS IS basis and OASIS DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. This is a working draft constructed by the editors. It is not an official committee work product and may not reflect the consensus opinion of the committee. Comments on this document may be sent to relax-ng-comment@lists.oasis-open.org. This specification defines elements and attributes that can be used as annotations in schemas. The purpose of these annotations is to support some of the features of XML 1.0 DTDs that are not supported by RELAX NG. Working Draft 4 August 2001

RELAX NG provides an annotation capability. In a RELAX NG schema, RELAX NG-defined elements can be annotated with child elements and attributes from other namespaces. The goal of this specification is to facilitate transition from XML 1.0 DTDs to RELAX NG schemas by defining annotations that support some of the features of XML 1.0 DTDs that are not supported by RELAX NG. RELAX NG itself performs only validation: it does not change the infoset of an XML document. Most of the features of XML 1.0 DTDs that are not supported by RELAX NG involve modification to the infoset. In XML 1.0, validation and infoset modification are combined in a monolithic XML processor. It is a goal of this specification to provide a clean separation between validation and infoset modification, so that a wide variety of implementation scenarios are possible. In particular, it should be possible to perform RELAX NG validation either before or after the infoset modifications implied by annotations. It should also be possible for an implementation of this specification not to modify the infoset at all and instead provide the application with a description of the modifications implied by the annotations, independently of any particular instance. This specification does not provide any support for features of XML 1.0 DTDs, such as entity declarations, that cannot be cleanly separated from validation. In an XML 1.0 document that is valid with respect to a DTD, each element or attribute in the instance has a unique corresponding element or attribute declaration in the DTD. With RELAX NG this is not always the case: it may be ambiguous which element or attribute pattern any particular element or attribute in the instance matches. In addition, it is non-trivial to determine when a RELAX NG schema is ambiguous. A further complication is that even when cases where it is not ambiguous, it may require multiple passes or lookahead to determine which element or attribute pattern a particular element or attribute matches. Detecting this situation is also non-trivial. Some features of XML 1.0 DTDs, in particular default attribute values and ID/IDREF/IDREFS validation, depend crucially on this unambiguous correspondence between elements or attributes in the instance and their corresponding declarations. In order to support these features by means of annotations on RELAX NG patterns, it is therefore necessary to impose restrictions on the use of such annotations. The goals in framing these restrictions were as follows: It must be possible to determine whether a schema satisfies the restrictions independently of any particular instance. Processing of the instance must not require lookahead or multiple passes. The modified infoset must be XML 1.0 compatible: it must be an infoset that could have been produced by a validating XML 1.0 parser for some DTD. Implementation of the restrictions should be straightforward. The restrictions should not be any more restrictive than necessary. The elements and attributes defined in this specification have the namespace URI. http://relaxng.org/ns/annotation/0.9 Examples in this specification follow the convention of using the prefix a to refer to this namespace URI.

The following DTD ]>]]> could be translated to the following RELAX NG schema with annotations: A list of employees. An individual employee. US JP ]]>

This specification defines three features: attribute default value ID/IDREF/IDREFS documentation Conformance is defined separately for each feature. A conformant implementation can support any combination of features. There are also two levels of conformance. Level 1 requires validation only. An implementation that supports a feature at level 1 is only required to check that the schema uses the feature correctly and that the instance is valid with respect to the schema's use of the feature. Level 2 requires that an implementation provide information about the infoset modifications implied by annotations. An implementation can provide the application either with a modified infoset or with sufficient information that would allow the application to modify the infoset itself. A conformant implementation may support different features at different levels. A conformant implementation may be an integral part of a RELAX NG validator or may be a separate software module.

An a:defaultValue attribute on a RELAX NG attribute element specifies the default value for the attribute. If an attribute element has an a:defaultValue attribute, then, after schema simplification, its first child must be a name element the first child of the containing element element must be a name element the value of the a:defaultValue attribute must match the pattern contained in the attribute element the pattern in the attribute element must not contain data or value elements with context-dependent datatypes it must not have an a:attributeType attribute (see ) it must not have a oneOrMore ancestor any ancestor that is a choice element must have one child that is an empty element it must have at least one choice ancestor if the containing definition competes with another definition, then that other definition must also contain an attribute element with the same name and with an a:defaultValue attribute with the same value. A definition <define name="ln1"> <element> nc1 p1 </element> </define> competes with a definition <define name="ln2"> <element> nc2 p2 </element> </define> if there is a name n that belongs to both nc1 and nc2. The a:defaultValue annotation implies a modification of the infoset that adds attribute information items for omitted attributes. Define this more precisely.

An a:attributeType attribute on a RELAX NG attribute element must have the value ID, IDREF or IDREFS. It specifies the XML 1.0 attribute type of the attribute and corresponds to the [attribute type] infoset property. Should we allow other attribute types such as NOTATION? Leading and trailing whitespace is ignored in the value of the a:attributeType element during schema simplification. If an attribute element has an a:attributeType attribute, then, after schema simplification, its first child must be a name element the first child of the containing element element must be a name element if the value of the a:attributeType attribute is ID, then there must not be a definition that competes with the definition containing the attribute element and that contains an attribute element that has a different name and an a:attributeType attribute with value ID. Note that a definition competes with itself. This implies that in the instance if two attributes are both IDs and have a parent element with the same name, then the two attributes must have the same name. any competing attribute element must have an a:attributeType attribute with the same value. Two attribute elements <attribute> nc1 p1 </attribute> and <attribute> nc2 p2 </attribute> compete if and only if the containing definitions compete and there is a name n that belongs to both nc1 and nc2. Note that a definition competes with itself. it must not have an a:defaultValue attribute (see ) An instance is valid with respect to the a:attributeType attributes in the schema if the attribute values in the instance declared by a:attributeType attributes in the schema to be of type ID, IDREF or IDREFS meet the validity constraints specified in for values of that type, after normalizing the values by applying the normalizeWhiteSpace function defined in . The a:attributeType annotation implies a modification of the infoset that changes the [attribute type] property of attribute information items to ID, IDREF or IDREFS and modifies the [normalized value] by applying the normalizeWhiteSpace function. Define this more precisely.

The a:documentation element can be used to specify human-readable documentation. It supports the functionality provided by comments in XML 1.0 DTDs. An a:documentation element must not contain any elements. It can have any attributes whose namespace URI is neither the empty string, the RELAX NG namespace URI nor the RELAX NG annotation namespace URI. In particular, it may have an xml:lang attribute. The documentation specified in an a:documentation element applies to the parent of the a:documentation element. To apply documentation to a value element, wrap the value element in a group element. To apply documentation to a name element, wrap the name element in a choice element. Is there a better solution? Allow an a:documentation attribute as an alternative? A RELAX NG element may have multiple a:documentation child elements, but all a:documentation child elements must precede all child elements from the RELAX NG namespace.

To be supplied. RELAX NGJames Clark, Makoto MURATA, editors. RELAX NG Specification. OASIS, 2001. XML 1.0Tim Bray, Jean Paoli, and C. M. Sperberg-McQueen, Eve Maler, editors. Extensible Markup Language (XML) 1.0 Second Edition. W3C (World Wide Web Consortium), 2000. XML InfosetJohn Cowan, Richard Tobin, editors. XML Information Set. W3C (World Wide Web Consortium), 2001.