ISO/IEC 19757-3:2006
(Main)Information technology — Document Schema Definition Languages (DSDL) — Part 3: Rule-based validation — Schematron
Information technology — Document Schema Definition Languages (DSDL) — Part 3: Rule-based validation — Schematron
ISO/IEC 19757 defines a set of Document Schema Definition Languages (DSDL) that can be used to specify one or more validation processes performed against Extensible Markup Language (XML) or Standard Generalized Markup Language (SGML) documents. (XML is an application profile SGML, ISO 8879:1986.) ISO/IEC 19757-3:2006 specifies Schematron, a rules-based schema language for XML. It establishes requirements for Schematron schemas and specifies when an XML document matches the patterns specified by a Schematron schema.
Technologies de l'information — Langages de définition de schéma de documents (DSDL) — Partie 3: Validation de règles orientées — Schematron
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Standards Content (Sample)
INTERNATIONAL ISO/IEC
STANDARD 19757-3
First edition
2006-06-01
Information technology — Document
Schema Definition Languages (DSDL) —
Part 3:
Rule-based validation — Schematron
Technologies de l'information — Langages de définition de schéma de
documents (DSDL) —
Partie 3: Validation de règles orientées — Schematron
Reference number
ISO/IEC 19757-3:2006(E)
©
ISO/IEC 2006
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ISO/IEC 19757-3:2006(E)
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ISO/IEC 19757-3:2006(E)
Contents
Foreword. v
Introduction. vi
1 Scope. 1
2 Normative references. 1
3 Terms and definitions. 1
4 Notation. 3
4.1 XPath. 3
4.2 Predicate Logic. 3
5 Syntax. 4
5.1 Well-formedness. 4
5.2 Namespace. 4
5.3 Whitespace. 4
5.4 Core Elements. 4
5.4.1 active element. 4
5.4.2 assert element. 4
5.4.3 extends element. 5
5.4.4 include element. 5
5.4.5 let element. 5
5.4.6 name element. 5
5.4.7 ns element. 5
5.4.8 param element. 6
5.4.9 pattern element. 6
5.4.10 phase element. 8
5.4.11 report element. 8
5.4.12 rule element. 8
5.4.13 schema element. 8
5.4.14 value-of element. 9
5.5 Ancillary Elements and Attributes. 9
5.5.1 diagnostic element. 9
5.5.2 diagnostics element. 9
5.5.3 dir element. 9
5.5.4 emph element. 9
5.5.5 flag attribute. 9
5.5.6 fpi attribute. 10
5.5.7 icon attribute. 10
5.5.8 p element. 10
5.5.9 role attribute. 10
5.5.10 see attribute. 10
5.5.11 span element. 10
5.5.12 subject attribute. 10
5.5.13 title element. 10
6 Semantics. 11
6.1 Validation Function. 11
6.2 Minimal Syntax. 11
6.3 Schema Semantics. 12
6.4 Query Language Binding. 12
6.5 Order and side-effects. 13
7 Conformance. 14
7.1 Simple Conformance. 14
7.2 Full Conformance. 14
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ISO/IEC 19757-3:2006(E)
Annex A (normative) RELAX NG schema for Schematron. 15
Annex B (normative) Schematron Schema for Additional Constraints. 19
Annex C (normative) Default Query Language Binding. 21
Annex D (informative) Schematron Validation Report Language. 22
D.1 Description. 22
D.2 RELAX NG Compact Syntax Schema. 22
D.3 Schematron Schema. 23
Annex E (informative) Design Requirements. 27
Annex F (normative) Use of Schematron as a Vocabulary. 28
Annex G (informative) Use of Schematron for Multi-Lingual Schemas. 29
Bibliography. 30
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ISO/IEC 19757-3:2006(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 19757-3 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 34, Document description and processing languages.
ISO/IEC 19757 consists of the following parts, under the general title Information technology — Document
Schema Definition Languages (DSDL):
⎯ Part 1: Overview
⎯ Part 2: Regular-grammar-based validation — RELAX NG
⎯ Part 3: Rule-based validation — Schematron
⎯ Part 4: Namespace-based Validation Dispatching Language — NVDL
The following parts are under preparation:
⎯ Part 5: Datatypes
⎯ Part 6: Path-based integrity constraints
⎯ Part 7: Character repertoire description language — CRDL
⎯ Part 8: Document schema renaming language — DSRL
⎯ Part 9: Datatype- and namespace-aware DTDs
⎯ Part 10: Validation management
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ISO/IEC 19757-3:2006(E)
Introduction
ISO/IEC 19757 defines a set of Document Schema Definition Languages (DSDL) that can be used to specify one or
more validation processes performed against Extensible Markup Language (XML) or Standard Generalized Markup
Language (SGML) documents. (XML is an application profile SGML, ISO 8879:1986.)
A document model is an expression of the constraints to be placed on the structure and content of documents to be
validated with the model. A number of technologies have been developed through various formal and informal consortia
since the development of Document Type Definitions (DTD) as part of ISO 8879, notably by the World Wide Web
Consortium (W3C) and the Organization for the Advancement of Structured Information Standards (OASIS). A number
of validation technologies are standardized in DSDL to complement those already available as standards or from
industry.
To validate that a structured document conforms to specified constraints in structure and content relieves the potentially
many applications acting on the document from having to duplicate the task of confirming that such requirements
have been met. Historically, such tasks and expressions have been developed and utilized in isolation, without
consideration of how the features and functionality available in other technologies might enhance validation objectives.
The main objective of ISO/IEC 19757 is to bring together different validation-related tasks and expressions to form a
single extensible framework that allows technologies to work in series or in parallel to produce a single or a set of
validation results. The extensibility of DSDL accommodates validation technologies not yet designed or specified.
In the past, different design and use criteria have led users to choose different validation technologies for different
portions of their information. Bringing together information within a single XML document sometimes prevents existing
document models from being used to validate sections of data. By providing an integrated suite of constraint description
languages that can be applied to different subsets of a single XML document, ISO/IEC 19757 allows different validation
technologies to be integrated under a well-defined validation policy.
[1] [2]
This part of ISO/IEC 19757 is based on the Schematron assertion language. The let element is based on XCSL .
Other features arise from the half-dozen early Open Source implementations of Schematron in diverse programming
languages and from discussions in electronic forums by Schematron users and implementers.
The structure of this part of ISO/IEC 19757 is as follows. Clause 5 describes the syntax of an ISO Schematron schema.
Clause 6 describes the semantics of a correct ISO Schematron schema; the semantics specify when a document is
valid with respect to an ISO Schematron schema. Clause 7 describes conformance requirements for implementations
of ISO Schematron validators. Annex A is a normative annex providing the ISO/IEC 19757-2 (RELAX NG) schema
for ISO Schematron. Annex B is a normative annex providing the ISO Schematron schema for constraints in ISO
Schematron that cannot be expressed by the schema of Annex A. Annex C is a normative annex providing the default
query language binding to XSLT. Annex D is an informative annex providing a ISO/IEC 19757-2 (RELAX NG
compact syntax) schema and corresponding ISO Schematron schema for a simple XML language Schematron
Validation Report Language. Annex E is an informative annex providing motivating design requirements for ISO
Schematron. Annex F is a normative annex allowing certain Schematron elements to be used in external
vocabularies. Annex G is an informative annex with a simple example of a multi-lingual schema.
Considered as a document type, a Schematron schema contains natural-language assertions concerning a set of
documents, marked up with various elements and attributes for testing these natural-language assertions, and for
simplifying and grouping assertions.
Considered theoretically, a Schematron schema reduces to a non-chaining rule system whose terms are Boolean
functions invoking an external query language on the instance and other visible XML documents, with syntactic
features to reduce specification size and to allow efficient implementation.
Considered analytically, Schematron has two characteristic high-level abstractions: the pattern and the phase. These
allow the representation of non-regular, non-sequential constraints that ISO/IEC 19757-2 cannot specify, and
various dynamic or contingent constraints.
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INTERNATIONAL STANDARD ISO/IEC 19757-3:2006(E)
Information technology — Document Schema Definition
Languages (DSDL) —
Part 3:
Rule-based validation — Schematron
1 Scope
This part of ISO/IEC 19757 specifies Schematron, a schema language for XML. This part of ISO/IEC 19757 establishes
requirements for Schematron schemas and specifies when an XML document matches the patterns specified by a
Schematron schema.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references,
only the edition cited applies. For undated references, the latest edition of the referenced document (including any
amendments) applies.
NOTE Each of the following documents has a unique identifier that is used to cite the document in the text. The
unique identifier consists of the part of the reference up to the first comma.
W3C XML 1.0, Extensible Markup Language (XML) 1.0 (Third Edition), W3C Recommendation, 04 February 2004
XPath, XML Path Language (XPath) Version 1.0, W3C Recommendation, 16 November 1999
XSLT, XSL Transformations (XSLT) Version 1.0, W3C Recommendation, 16 November 1999
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 abstract pattern
pattern in a rule that has been parameterized to enable reuse
3.2 abstract rule
collection of assertions which can be included in other rules but which does not fire itself
3.3 active pattern
pattern belonging to the active phase
3.4 active phase
one particular phase, whose patterns are used for validation
3.5 assertion
natural-language assertion with corresponding assertion test and ancillary attributes: assertions are marked up
with assert and report elements
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ISO/IEC 19757-3:2006(E)
3.6 assertion test
assertion modelled or implemented by a Boolean query; an assertion test "succeeds" or "fails"
3.7 correct schema
schema that satisfies all the requirements of this part of ISO/IEC 19757
3.8 diagnostic
named natural language statements providing information to end-users of validators concerning the expected and
actual values together with repair hints
3.9 elaborated rule context expression
single rule context expression which explicitly disallows items selected by lexically previous rule contexts in the same
pattern
3.10 good schema
correct schema with queries which terminate and do not add constraints to those of the natural-language assertions.
NOTE It may not be possible to compute that a schema is good.
3.11 implementation
implementation of a Schematron validator
3.12 name
token with no whitespace characters
3.13 natural-language assertion
natural-language statement expressing some part of a pattern; a natural-language assertion is "met" or "unmet"
3.14 pattern
named structure in instances specified in a schema by a lexically-ordered collection of rules
3.15 phase
named, unordered collection of patterns; patterns may belong to more than one phase; two names, #ALL and
#DEFAULT, are reserved with particular meanings
3.16 progressive validation
validation of constraints in stages determined or grouped to some extent by the schema author rather than, for
example, entirely determined by document order
3.17 query language binding
named set, specified in a document called a Query Language Binding, of the languages and conventions used for
assertion tests, rule-context expressions and so on, by a particular Schematron implementation
NOTE 1 Schematron is defined as a framework, with a default query language binding, but other query language bindings are
possible.
NOTE 2 6.4 specifies the information to be required by a query language binding and Annex C defines the default query language
binding for Schematron.
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ISO/IEC 19757-3:2006(E)
3.18 rule
unordered collection of assertions with a rule-context expression and ancillary attributes
3.19 rule context
element or other information item used for assertion tests; a rule is said to fire when an information item matches the
rule context
3.20 rule-context expression
a query to specify subjects; a rule-context is said to match an information item when that information item has not
been matched by any lexically-previous rule context expressions in the same pattern and the information item is one
of the information items that the query would specify
3.21 schema
specification of a set of XML documents
3.22 subject
particular information item which corresponds to the object of interest of the natural-language assertions and typically
is matched by the context expression of a rule
3.23 valid with respect to a schema
member of the set of XML documents described by the schema: an instance document is valid if no assertion tests
in fired rules of active patterns fail
3.24 variable
constant value, evaluated within the parent schema, phase, pattern or rule and scoped within the parent schema,
phase, pattern or rule
4 Notation
4.1 XPath
This part of ISO/IEC 19757 uses XPath to identify information items in Schematron schemas.
4.2 Predicate Logic
This part of ISO/IEC 19757 uses predicate logic to express the semantics of Schematron schema. The following
symbols are defined for use in s6.3:
—
()
Grouping delimiters
—
∀
"for all". Prefix operator.
—
¬
"not". Prefix operator.
—
∈
"is member of", in set operative sense. Prefix operator.
3
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ISO/IEC 19757-3:2006(E)
—
,
"and" (sequence). Infix operator.
—
:
"where". Such that. Infix operator.
—
⇔
"if and only if". Infix operator.
5 Syntax
5.1 Well-formedness
A Schematron schema shall be a well-formed XML document, according to the version of XML used.
5.2 Namespace
All elements shown in the grammar for Schematron are qualified with the namespace URI:
http://purl.oclc.org/dsdl/schematron
In subsequent clauses, the prefix sch is taken as bound to the Schematron namespace URI for exposition purposes.
The prefix sch is not reserved or required by this part of ISO/IEC 19757.
Any element can also have foreign attributes in addition to the attributes shown in the grammar. A foreign attribute is
an attribute with a name whose namespace URI is neither the empty string nor the Schematron namespace URI. Any
non-empty element may have foreign child elements in addition to the child elements shown in the grammar. A foreign
element is an element with a name whose namespace URI is not the Schematron namespace URI. There are no
constraints on the relative position of foreign child elements with respect to other child elements.
5.3 Whitespace
Any element can also have as children strings that consist entirely of whitespace characters, where a whitespace
character is one of U+0020, U+0009, U+000D or U+000A. There are no constraints on the relative position of
whitespace string children with respect to child elements.
NOTE Leading and trailing whitespace should be stripped from attributes defined by this part. Whitespace should be collapsed
in elements defined by this part that allow text. Whitespace may be stripped from elements defined by this part that
do not allow text.
5.4 Core Elements
The grammar for Schematron elements is given in Annex A.
5.4.1 active element
The required pattern attribute is a reference to a pattern that is active in the current phase.
5.4.2 assert element
An assertion made about the context nodes. The data content is a natural-language assertion. The required test
attribute is an assertion test evaluated in the current context. If the test evaluates positive, the assertion succeeds.
The optional diagnostics attribute is a reference to further diagnostic information.
The natural-language assertion shall be a positive statement of a constraint.
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ISO/IEC 19757-3:2006(E)
NOTE The natural-language assertion may contain information about actual values in addition to expected values and may
contain diagnostic information. Users should note, however, that the diagnostic element is provided for such
information to encourage clear statement of the natural-language assertion.
The icon, see and fpi attributes allow rich interfaces and documentation. They are defined below.
The flag attribute allows more detailed outcomes. It is defined below.
The role and subject attributes allow explicit identification of some part of a pattern. They are defined below.
5.4.3 extends element
Abstract rules are named lists of assertions without a context expression. The required rule attribute references an
abstract rule. The current rule uses all the assertions from the abstract rule it extends.
5.4.4 include element
The required href attribute references an external well-formed XML document whose document element is a
Schematron element of a type which is allowed by the grammar for Schematron at the current position in the schema.
The external document is inserted in place of the include element.
5.4.5 let element
A declaration of a named variable. If the let element is the child of a rule element, the variable is calculated and
scoped to the current rule and context. Otherwise, the variable is calculated with the context of the instance document
root.
The required name attribute is the name of the variable. The required value attribute is an expression evaluated in
the current context.
It is an error to reference a variable that has not been defined in the current schema, phase, pattern, or rule, if the
query language binding allows this to be determined reliably. It is an error for a variable to be multiply defined in the
current schema, phase, pattern and rule.
The variable is substituted into assertion tests and other expressions in the same rule before the test or expression
is evaluated. The query language binding specifies which lexical conventions are used to detect references to variables.
An implementation may provide a facility to override the values of top-level variables specified by let elements under
the schema element. For example, an implementation may allow top-level variables to be supplied on the command
line. The values provided are strings or data objects, not expressions.
5.4.6 name element
Provides the names of nodes from the instance document to allow clearer assertions and diagnostics. The optional
path attribute is an expression evaluated in the current context that returns a string that is the name of a node. In
the latter case, the name of the node is used.
An implementation which does not report natural-language assertions is not required to make use of this element.
5.4.7 ns element
Specification of a namespace prefix and URI. The required prefix attribute is an XML name with no colon character.
The required uri attribute is a namespace URI.
NOTE Because the characters allowed as names may change in versions of XML subsequent to W3C XML 1.0, the
ISO/IEC 19757-2 (RELAX NG Compact Syntax) schema for Schematron does not constrain the prefix to particular characters.
In an ISO Schematron schema, namespace prefixes in context expressions, assertion tests and other query expressions
should use the namespace bindings provided by this element. Namespace prefixes should not use the namespace
bindings in scope for element and attribute names.
5
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