This standard uses to express the names of information items in the schema. In this standard the prefix sch is bound to the Schematron namespace URI.

This standard uses predicate logic to express the semantics of Schematron schema. The following functions are defined:

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 Schematron-namespace attribute, and shall be stripped. Whitespace in Schematron-namespace elements should be collapsed.

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 XML documents addressed using information in the instance or schema

• 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.

To simplifying the specification of semantics later, the following transformation steps are first applied to a schema, resulting in a schema in the simplified syntax:

1. Resolve all libraries by element inclusion

2. Resolve all abstract patterns by macro substitution

3. Resolve all abstract rules in the schema by element inclusion

4. Resolve all top-level parameters by text substitution

5. Negate all sch:report elements into sch:assert elements

6. Remove (ignore) all information items in foreign namespaces.

The resulting simplified syntax is also a valid Schematron instance in the full syntax. The simplified 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 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

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.

A Schematron implementation which does not support the specification language shall fail with an error.

A schema language binding may also provide the following:

• The data models of the various query languages, the conversion between data models, and the treatment of information items: which information items are stripped or ignored, which information items are errors, and which information items are used.

• 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 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.

The schema language binding may also specify the element types in other namespaces which provide query-language-specific ancilliary information or pragmatic hints.

The schema language binding shall specify any whitespace processing required on queries.

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 statement 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.

All queries shall act as pure functions. Queries shall not alter the instance in any way visible to other queries. this standard does not specify any outcome augmentation of the instance being validated.

The only element which has a side-effect is key, which may provide extra index information for other queries.

A simple-conformance implementation 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 Part 2 (RELAX NG) schema of this standard.

A simple-conformance implementation shall be able to determine for any XML document and for any good schema whether the document is valid with respect to the schema.

A full-conformance implementation shall be able to determine for any XML document whether it is a correct schema.

• A valid schema conforms to the constraints of , the normative Part 2 (RELAX NG) schema of this standard.

• A valid schema conforms to the constraints of , the normative ISO Schematron schema of this standard.

• A correct schema's attributes conform to the grammars specified by the query language binding in use.

A full-conformance implementation shall be able to determine for any XML document and for any good schema whether the document is valid with respect to the schema.