The structure of
Normative annexes provide RELAX NG and Schematron schemas for Schematron, and the default query language binding to XSLT.
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 as a document type, a Schematron schema contains natural language assertions concerning an instance, marked up with various elements and attributes for testing these assertions, and for simplifying and grouping the assertions.
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 Part 2 cannot specify, and various dynamic or contingent constraints.
The following referenced documents are indispensable for the
application of
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.
The definitions of Part 1 and Part 2
also apply to
sch
is bound to the Schematron namespace URI.
is member of, an infix relation, used in the set-operation sense.
The more familiar term "is element of" is not used,
to avoid confusion with XML elements.
Where y is an element in a simplified schema, x ∈ y
is defined here as the
child::x path from context of subject y
as defined by
x ∈ y is defined here as the path
//sch:pattern
when y has the special
value #ALL
x ∈ y is defined here as the path
//sch:pattern[@id=/sch:schema/@default-phase]
when the y has the special
value #DEFAULT
Otherwise x ∈ y is defined here as the path
../sch:pattern[@id=//sch:phase[id="y"]/active/@pattern]
where y is a name.
the XPath function position() of a rule r in its parent pattern
a function returning boolean provided by the query language binding: it returns true iff the subject s from the document d matches the context expression of rule r
a function returning boolean provided by the query language binding: it returns true iff the assertion a is true when applied to the subject s from the document d
All elements shown in the grammar are qualified with the namespace URI:
http://www.ascc.net/xml/schematron
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.
Any element can also have as children strings that consist entirely of whitespace characters, where a whitespace character is one of U+0020, U+009, U+00D or U+00A. There are no constraints on the relative position of whitespace string children with respect to child elements.
Leading and trailing whitespace is allowed for the value of any attribute, and shall be stripped.
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
empty
A Schematron validator is a function returning "valid", "invalid" or "error". The function performs notationally performs two steps: transforming the schema into a simple syntax, then testing the instance against the simple syntax.
A Schematron validator is a function over the following:
a query language binding
a schema document
an instance to be validated
external instances, if the query language invokes them
a phase name, or #ALL if all patterns shall be active patterns, or #DEFAULT if the phase attribute on the schema element shall be used
a list of name-value pairs, if the schema uses external variables.
A Schematron validator shall perform the following transformation steps on the schema, resulting in a schema in the simple syntax:
Resolve all libraries by element inclusion
Resolve all abstract patterns by macro substitution
Resolve all abstract rules in the schema by element inclusion
Resolve all top-level parameters by text substitution
Negate all sch:report elements into sch:assert elements
Remove (ignore) all elements in foreign namespaces.
The resulting simple syntax is also a valid Schematron instance in the full syntax. The simple syntax differs from the complex syntax by not containing the following XPaths:
//sch:library
//sch:pattern/@abstract="true"
//sch:rule/@abstract="true"
/sch:schema/sch:param
//sch:rule/sch:report
This clause gives the semantics of a good schema that has been transformed into the simple syntax.
A good schema with no use of keys or variables satisfies the following predicate:
∃ ( instance, schema, active-phase ),
∀( subject, pattern, rule, assertion ) :
subject ∈ instance,
subject ∈ schema,
pattern ∈ active-phase,
rule ∈ pattern,
assertion ∈ rule :
match ( rule, subject, instance )
∧ ( ∀(previous-rule ) :
previous-rule ∈ pattern,
position (previous-rule ) < position( rule ) :
¬ ( match ( previous-rule, subject, instance )))
⇒ assert ( assertion, subject, instance ) = true
In natural language, that is "There exists an instance, schema and active-phase combination where, for each subject, pattern, rule and assertion (the subject being a member of that instance, the pattern being a member of that schema, the pattern being a member of that active-phase, the rule being a member of that pattern, the assertion being a member of that rule), the following is true: if the subject in an instance matches the rule, and that subject has not been matched by a previous rule in the same pattern, then the particular assertion evaluates to true when applied to the particular subject and instance."
A query language binding shall provide the following:
The general query language used. A name token which identifies the query language. The data model.
The rule context query language. The rule context scope.
The assertion test, a function which returns a data value coerceable into boolean.
The following query language names are reserved and recommended:
xslt
exslt
xslt2
xpath
xpath2
xquery
A Schematron implementation which does not support the specification language shall fail with an error.
A schema language binding may provide the following:
The name query language, a function which returns a data value coerceable into a string.
The value-of query language, a function which returns a data value coerceable into a string.
The key path language.
The let value query language, a function which returns a data value.
The variable delimiter convention, a lexical convention such as a delimiter by which the use of a variable in a query expression shall be recognized.
The abstract pattern parameter convention, a lexical convention such as a delimiter by which the parameters of abstract patterns inside query expressions shall be recognized.
A Schematron implementation which does not support the specification language shall fail with an error.
The order in which elements are validated is implementation-dependent, without altering the validity of the instance.
The order in which patterns are used is implementation-dependent, without altering the validity of the instance
The order in which elaborated rule-contexts are matched is implementation-dependent, without altering the validity of the instance
The order in which assertions are tested is implementation-dependent, without altering the validity of the instance.
The only elements for which order is significant are the sch:rule and sch:let elements.
An sch:rule element acts as an if-then-else chain within each pattern. An implementation may make order non-significant by converting rules contexts to elaborated rule contexts. An elaborated rule context consists the negated union of all the lexically previous rule contexts in the same pattern interected with the current rule context.
An sch:let element may use lexically previous variables within the same rule or global variables.
A wide variety of implementation strategies are therefore possible.
All queries shall act as pure functions.
Queries shall not alter the instance in any
way visible to other queries.
The only element which has a side-effect is key, which may provide extra index information for other queries.
A full-conformance Schematron validator shall be able to determine for any XML document whether it is a correct schema.
A correct schema conforms to the constraints
of the normative RELAX NG schema of
A correct schema conforms to the constraints
of the normative Schematron schema of
A correct schema's attributes conform to the grammars specified by the query language binding in use.
A full-conformance Schematron validator shall be able to determine for any XML document and for any good schema whether the document is valid with respect to the schema.
It is not a requirement of
A simple-conformance Schematron validator shall be able to report for any XML document whether it may not be a valid Schematron schema.
A valid schema conforms to the constraints
of the normative RELAX NG schema of
A valid schema conforms to the constraints
of the normative Schematron schema of
A valid schema's attributes conform to the grammars specified by the query language binding in use.
A simple-conformance Schematron validator shall be able to determine for any XML document and for any good schema whether the document is valid with respect to the schema.
It is not a requirement of
A correct Schematron schema shall be valid with respect to the following RELAX NG schema.
RELAX NG schema for Schematron goes here
A correct Schematron schema shall be valid with respect to the following Schematron schema. This schema does not specify constraints which can be expressed by the RELAX NG schema for Schematron.
Schematron Schema for Schematron goes here
A Schematron schema with no language binding or a language binding with the value "xslt" shall use the following binding.
The query language used is the extended version of
The rule context is interpreted according to the production XXX of XSLT. The rule context may be elements, attributes, comments and processing instructions.
The assertion test is interpreted according to production XXX of XSLT.
The name query is interpreted according to production XXX of XSLT.
The value-of query is interpreted according to production XXX of XSLT.
The key path is interpreted according to production XXX of XSLT. A Schematron key is equivalent to an XSLT key.
The let value is interpreted according to production XXX of XSLT.
A Schematron let expression is treated as an XSLT variable. The XSLT $ delimiter signifies the use of a variables in an assertion test, name query or value-of query.
The notation for signifying abstract pattern is to prefix the token with the ????. This is a character not found in URLs or XPaths.