ISO/IEC 19757-3:2020

INTERNATIONAL ISO/IEC
STANDARD 19757-3
Third edition
2020-06
Information technology — Document
Schema Definition Languages
(DSDL) —
Part 3:
Rule-based validation using
Schematron
Technologies de l'information — Langages de définition de schéma de
documents (DSDL) —
Partie 3: Validation basée sur des règles à l'aide de Schematron
Reference number
©
ISO/IEC 2020
© ISO/IEC 2020
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ii © ISO/IEC 2020 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Notation . 4
5 Syntax . 4
5.1 Well-formedness. 4
5.2 Namespace. 4
5.3 Whitespace . 4
5.4 Core elements . 4
5.4.1 General. 4
5.4.2 active element . 4
5.4.3 assert element . 4
5.4.4 extends element . 5
5.4.5 include element . 5
5.4.6 let element . 5
5.4.7 name element. 5
5.4.8 ns element . 6
5.4.9 param element . 6
5.4.10 pattern element . 6
5.4.11 phase element . 6
5.4.12 report element . 6
5.4.13 rule element. 7
5.4.14 schema element . 7
5.4.15 value-of element . 7
5.5 Ancillary elements and attributes . 8
5.5.1 diagnostic element . 8
5.5.2 diagnostics element . 8
5.5.3 dir element . 8
5.5.4 emph element. 8
5.5.5 flag attribute . 8
5.5.6 fpi attribute . 8
5.5.7 icon attribute . 8
5.5.8 p element . 8
5.5.9 properties element . 8
5.5.10 property element . 8
5.5.11 role attribute . 9
5.5.12 see attribute . 9
5.5.13 span element. 9
5.5.14 subject attribute . 9
5.5.15 title element . 9
6 Semantics . 9
6.1 Validation function . 9
6.2 Minimal syntax (informative) .10
6.3 Abstract pattern processing .11
6.4 Query language binding .12
6.5 Order and side-effects .13
7 Conformance .13
7.1 Simple conformance .13
7.2 Full conformance.14
© ISO/IEC 2020 – All rights reserved iii

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 .20
Annex D (informative) Schematron Validation Report Language .21
Annex E (informative) Design requirements .26
Annex F (informative) Use of Schematron as a vocabulary .27
Annex G (informative) Use of Schematron for multi-lingual schemas .28
Annex H (normative) Query language binding for XSLT2 .29
Annex I (normative) Query language binding for XPath2 .31
Annex J (normative) Query language binding for XSLT3 .32
Annex K (normative) Query language binding for XPath3 .34
Annex L (informative) Query language binding for EXSLT.35
Annex M (informative) Query language binding for STX .36
Annex N (informative) Example usage of Schematron properties .37
Bibliography .39
iv © ISO/IEC 2020 – All rights reserved

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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for
the different types of document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www .iso .org/ patents) or the IEC
list of patent declarations received (see http:// patents .iec .ch).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 34, Document description and processing languages.
This third edition cancels and replaces the second edition (ISO/IEC 19757-3:2016), which has been
technically revised.
The main changes compared to the previous edition are as follows:
— query language bindings have been added for XSLT 3.0 (Annex J) and XPath 3.0 (Annex K);
— annexes pertaining to XPath and XSLT query language bindings (Annexes H to K) are now all
normative, while those for EXSLT (Annex L) and STX (Annex M) remain informative.
A list of all parts in the ISO/IEC 19757 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO/IEC 2020 – All rights reserved v

Introduction
ISO/IEC 19757 (all parts) 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 (see ISO 8879).]
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 (DTDs)
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 the industry.
Through the validation that a structured document conforms to specified constraints in structure and
content, the potentially many applications acting on the document are relieved from duplicating 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 can enhance validation objectives.
The main objective of ISO/IEC 19757 (all parts) 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 (all parts) allows different validation technologies to
be integrated under a well-defined validation policy.
The structure of this document 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 provides the ISO/IEC 19757-2
(RELAX NG) schema for ISO Schematron. Annex B provides the ISO Schematron schema for constraints
in ISO Schematron that cannot be expressed by the schema of Annex A. Annex C provides the default
query language binding to XSLT1. Annex D provides an 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 provides motivating design requirements for ISO Schematron. Annex F
specifies certain Schematron elements to be used in external vocabularies. Annex G provides a simple
example of a multi-lingual schema. Annexes H to M provide query language bindings. Annex N shows
example usage of Schematron properties.
This edition is backwards compatible with ISO/IEC 19757-3:2016, supersedes it and provides extra
query language bindings, in particular for XSLT3.
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.
vi © ISO/IEC 2020 – All rights reserved

[2] [4]
This document 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.
© ISO/IEC 2020 – All rights reserved vii

INTERNATIONAL STANDARD ISO/IEC 19757-3:2020(E)
Information technology — Document Schema Definition
Languages (DSDL) —
Part 3:
Rule-based validation using Schematron
1 Scope
This document specifies Schematron, a schema language for XML. This document establishes
requirements for Schematron schemas and specifies when an XML document matches the patterns
specified by a Schematron schema. Schematron uses query languages such as XPath for writing
assertions.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
1)
XPath , XML Path Language (XPath) Version 1.0, W3C Recommendation, 16 November 1999
2)
XPath2 , XML Path Language (XPath) 2.0, W3C Recommendation, 23 January 2007
3)
XPath3 , XML Path Language (XPath) 3.0, W3C Recommendation, 8 April 2014
4)
XPath2 Functions , XQuery 1.0 and XPath 2.0 Functions and Operators, W3C Recommendation, 23
January 2007
5)
XPath3 Functions , XPath and XQuery Functions and Operators 3.0, W3C Recommendation, 8 April 2014
6)
XSLT1 , XSL Transformations (XSLT) Version 1.0, W3C Recommendation, 16 November 1999
7)
XSLT2 , XSL Transformations (XSLT) Version 2.0, W3C Recommendation, 23 January 2007
8)
XSLT3 , XSL Transformations (XSLT) Version 3.0, W3C Recommendation, 8 June 2017
ISO/IEC 19757-2, Information technology — Document Schema Definition Language (DSDL) — Part 2:
Regular-grammar-based validation — RELAX NG
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
1) Available at http:// www .w3 .org/ TR/ xpath.
2) Available at http:// www .w3 .org/ TR/ xpath20/ .
3) Available at https:// www .w3 .org/ TR/ xpath -30/ .
4) Available at http:// www .w3 .org/ TR/ xpath -functions/ .
5) Available at https:// www .w3 .org/ TR/ xpath -functions -30/ .
6) Available at http:// www .w3 .org/ TR/ xslt.
7) Available at http:// www .w3 .org/ TR/ xslt20/ .
8) Available at .https:// www .w3 .org/ TR/ xslt -30/ .
© ISO/IEC 2020 – All rights reserved 1

ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
abstract pattern
pattern (3.13) in a rule (3.18) that has been parameterized to enable reuse
3.2
abstract rule
collection of assertions (3.5) which can be included in other rules (3.18) but which does not fire itself
3.3
active pattern
pattern (3.13) belonging to the active phase (3.4)
3.4
active phase
phase (3.14) whose patterns (3.13) are used for validation
3.5
assertion
natural-language statement with associated assertion test (3.6) and ancillary attributes
3.6
assertion test
Boolean query
Note 1 to entry: An assertion test "succeeds" or "fails".
3.7
Schematron schema
document that satisfies all the requirements of this document
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 (3.20) which explicitly disallows items selected by lexically previous rule
contexts (3.19) in the same pattern (3.13)
3.10
implementation
implementation of a Schematron validator
3.11
name
mixture of name characters with a restricted set of initial characters
Note 1 to entry: See Production 5 of XML1.
3.12
natural-language assertion
natural-language statement expressing some part of a pattern (3.13)
Note 1 to entry: A natural-language assertion is "met" or "unmet".
2 © ISO/IEC 2020 – All rights reserved

3.13
pattern
unordered collection of rules (3.18) with an optional identifier and ancillary information
3.14
phase
named, unordered collection of patterns (3.13)
Note 1 to entry: Patterns may belong to more than one phase.
Note 2 to entry: Two strings, #ALL and #DEFAULT, are reserved with particular meanings.
3.15
progressive validation
validation of constraints in stages determined or grouped to some extent by the schema author rather
than, for example, entirely determined by the document order
3.16
property
named data giving additional metadata on an assertion (3.5) or report
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 (3.6), rule-context expressions (3.20) and so on, by a particular Schematron
implementation (3.10)
3.18
rule
unordered collection of assertions (3.5) with a rule-context expression (3.20) and ancillary attributes
3.19
rule context
element or other information item used for assertion tests (3.6)
Note 1 to entry: A rule is said to fire when an information item matches the rule context.
3.20
rule-context expression
query to specify subjects (3.21)
Note 1 to entry: A rule context (3.19) 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 (3.13) and the information
item is one of the information items that the query would specify.
3.21
subject
particular information item which corresponds to the object of interest of the natural-language
assertions (3.12) and typically is matched by the context expression of a rule (3.18)
3.22
valid
passing all assertion tests (3.6) in fired rules (3.18) of active patterns (3.3)
3.23
variable
constant value, represented by a name (3.11), evaluated within the parent schema, phase (3.14), pattern
(3.13) or rule (3.18) and scoped within the parent schema, phase, pattern or rule
© ISO/IEC 2020 – All rights reserved 3

4 Notation
This document uses XPath to identify information items, to the extent that items in the XPath data
model can be derived from those defined by XML Infoset, in Schematron schemas.
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 [IRI]:
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 document. 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 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 should be stripped from attributes defined by this document.
Whitespace should be collapsed in elements defined by this document that allow text. Whitespace may
be stripped from elements defined by this document that do not allow text.
5.4 Core elements
5.4.1 General
A Schematron schema shall follow the grammar given in Annex A.
For information on the use of Schematron elements in external vocabularies, see Annex F.
5.4.2 active element
The required pattern attribute is a reference to a pattern that is active in the current phase.
5.4.3 assert element
This element indicates 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.
The icon, see and fpi attributes (5.5.7, 5.5.12 and 5.5.6) allow rich interfaces and documentation.
4 © ISO/IEC 2020 – All rights reserved

The flag attribute (5.5.5) allows more detailed outcomes.
The role and subject attributes (5.5.11 and 5.5.14) allow explicit identification of some part of a
pattern.
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.
5.4.4 extends element
The extends element allows reference to the contents of other declarations. The extends element shall
either have an href attribute or a rule attribute but not both.
Abstract rules are named lists of assertions without a context expression. An extends element with a
rule attribute shall reference an abstract rule. The current rule uses all the assertions from the abstract
rule it extends.
An extends element with an href attribute shall reference external declarations. The href attribute is
an IRI reference to an external well-formed XML document or to an element in an external well-formed
XML document that is a Schematron element of the same type as the parent element of the extends
element. The contents of that referenced element shall be inserted in place of the extends element.
In such a case, the relative position of elements in the post-inclusion document may be to that extent
invalid against the schema for Schematron in Annex A; however, other schema constraints such as
containment shall still apply.
5.4.5 include element
The required href attribute shall be an IRI reference to a well-formed XML document or to an element
in a well-formed XML document.
The referenced element shall be inserted in place of the include element. The referenced element shall
be a type which is allowed by the grammar for Schematron at the location of the include element.
5.4.6 let element
The let element declares 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 value attribute is an expression evaluated
in the current context. If no value attribute is specified, the value of the attribute is the element content
of the let element.
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.
5.4.7 name element
The 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. If the path attribute is omitted, the name of the context node
is used.
© ISO/IEC 2020 – All rights reserved 5

5.4.8 ns element
The ns element specifies 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 [IRI].
Namespace prefixes in context expressions, assertion tests and other query expressions shall be defined
by this element. Namespace prefixes should not use the namespace bindings in scope for element and
attribute names.
NOTE 1 Namespace declarations as specified in XML 1.0 Namespaces (e.g. xmlns:foo="http://www.
example.com") do not apply to namespace prefixes in context expressions, assertion tests and other query
expressions.
NOTE 2 Because the characters allowed as names can 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.
5.4.9 param element
The param element specifies a name-value pair providing parameters for an abstract pattern. The required
name attribute is an XML name with no colon. The required value attribute is a fragment of a query.
5.4.10 pattern element
The id attribute provides a unique name for the pattern and is required for abstract patterns. The child
rule elements of a pattern give constraints that are in some way related.
The optional documents attribute provides IRIs of the subordinate documents the rule contexts are
relative to. If the expression evaluates to more than one IRI, then the pattern is sought in each of the
documents. The documents attribute is evaluated in the context of the original instance document root.
The icon, see and fpi attributes (5.5.7, 5.5.12 and 5.5.6) allow rich interfaces and documentation.
When a pattern element has the attribute abstract with a value true, then the pattern defines an
abstract pattern. An abstract pattern shall not have an is-a attribute and shall have an id attribute.
5.4.11 phase element
The phase element provides the means to declare named groups of patterns, for example to support
progressive validation. Additional information on design requirements for progressive validation is
provided in Annex E.
The required id attribute is the name of the phase. The element specifies the phase to be used for
validating documents, for example, by user command.
Two strings, #ALL and #DEFAULT, have special meanings when specifying active phases. The string #ALL
is reserved to denote that all patterns are active. The string #DEFAULT is to denote that the name given
in the defaultPhase attribute on the schema element should be used. If no defaultPhase is specified,
then all patterns are active.
The icon, see and fpi attributes (5.5.7, 5.5.12 and 5.5.6) allow rich interfaces and documentation.
The strings #ALL and #DEFAULT shall not be used as phase names in a Schematron schema. They are for
use when invoking or configuring schema validation, for example, as a command-line parameter.
5.4.12 report element
The report element specifies 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 report succeeds. The optional diagnostics attribute is a reference to
further diagnostic information.
6 © ISO/IEC 2020 – All rights reserved

The natural-language assertion shall be a positive statement of a found pattern or a negative statement
of a constraint.
The icon, see and fpi attributes (5.5.7, 5.5.12 and 5.5.6) allow rich interfaces and documentation.
The flag attribute (5.5.5) allows more detailed outcomes.
The role and subject attributes (5.5.11 and 5.5.14) allow explicit identification of some part of a
pattern.
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.
5.4.13 rule element
The rule element provides a list of assertions tested within the context specified by the context
attribute. The context attribute, required unless the rule element has the attribute abstract with a
value true, specifies the rule-context expression.
The icon, see and fpi attributes (5.5.7, 5.5.12 and 5.5.6) allow rich interfaces and documentation.
The flag attribute (5.5.5) allows more detailed outcomes.
The role and subject attributes (5.5.11 and 5.5.14) allow explicit identification of some part of a pattern
as part of the validation outcome.
When the rule element has the attribute abstract with a value true, then the rule is an abstract rule.
An abstract rule shall not have a context attribute. An abstract rule is a list of assertions that will be
invoked by other rules belonging to the same pattern using the extends element. Abstract rules provide
a mechanism for reducing schema size.
It is not an error if a rule never fires in a document. In order to test that a document always has some
context, a new pattern should be created from the context of the document, with an assertion requiring
the element or attribute.
5.4.14 schema element
The schema element is the top-level element of a Schematron schema.
The optional schemaVersion attribute gives the version of the schema. Its allowed values are not defined
by this document and its use is implementation-dependent.
The optional queryBinding attribute provides the short name of the query language binding in use. The
defaultPhase attribute may be used to indicate the phase to use in the absence of explicit user-supplied
information.
The icon, see and fpi attributes (5.5.7, 5.5.12 and 5.5.6) allow rich interfaces and documentation.
5.4.15 value-of element
The value-of element finds or calculates values from the instance document to allow clearer assertions
and diagnostics. The required select attribute is an expression evaluated in the current context that
returns a string.
Variable references in the select attribute are resolved in the scope of the current schema, phase,
pattern and rule.
© ISO/IEC 2020 – All rights reserved 7

5.5 Ancillary elements and attributes
5.5.1 diagnostic element
The diagnostic element provides a natural-language message giving more specific details concerning a
failed assertion, such as found versus expected values and repair hints.
NOTE 1 Diagnostics in multiple languages can be supported by using a different diagnostic element for each
language, with the appropriate xml:lang language attribute, and referencing all the unique identifiers of the
diagnostic elements in the diagnostics attribute of the assertion. Annex G gives a simple example of a multi-
lingual schema.
NOTE 2 Typical values for the role attribute on a diagnostic element can be warning, caution or note.
5.5.2 diagnostics element
The diagnostics element provides a section containing individual diagnostic elements.
5.5.3 dir element
The dir element provides a section of natural-language text with a direction specified by the value
attribute. The value ltr indicates left-to-right text; the value rtl indicates right-to-left text.
5.5.4 emph element
The emph element encloses a portion of text that should be rendered with some emphasis.
5.5.5 flag attribute
The flag attribute acts as a Boolean variable with the initial value false. A flag is implicitly declared by
an assertion or rule having a flag attribute with that name. The value of a flag becomes true when an
assertion with that flag fails or a rule with that flag fires.
The purpose of flags is to convey state or severity information to a subsequent process.
5.5.6 fpi attribute
The fpi attribute contains a formal public identifier for the schema, phase or other element.
5.5.7 icon attribute
The icon attribute contains the location of a graphics file containing some visible representation of the
severity, significance or other grouping of the associated element.
5.5.8 p element
The p element represents a paragraph of natural language text containing maintainer and user
information about the parent element. The schema can nominate paragraphs that should be rendered
in a distinct way, keyed with the class attribute.
5.5.9 properties element
The properties element provides a section containing individual property elements.
5.5.10 property element
The property element declares additional arbitrary properties that will be associated with failed
assertions and successful reports.
8 © ISO/IEC 2020 – All rights reserved

The optional scheme attribute should be an IRI or other public identifier which specifies the notation
used for the metadata value.
NOTE 1 The property element is suitable for linking assertions or reports to actions, to additional metadata,
to datatyping, and to dynamically extracted text related to the subject.
NOTE 2 Where the property value contains elements in a well-known namespace or where the scheme
used is otherwise obvious or unnecessary, the scheme attribute can be omitted. For example, if the property
element contains an ISO/IEC 19757-7 Character Repertoire Description Language schema, no scheme attribute is
appropriate.
Properties are defined on assertions in order to associate assertion text with the property. A property of an
assert element typically should be information pertaining to validation. A property of a report element
typically should be information for document augmentation (post schema validation information set.)
NOTE 3 Properties do not participate in the validation of constraints.
For additional information on Schematron properties, see Annex N.
5.5.11 role attribute
The role attribute is a name describing the function of the assertion or context node in the pattern.
If the assertion has a subject attribute, then the role labels the arc between the context node and any
nodes which match the path expression given by the subject attribute.
5.5.12 see attribute
The see attribute contains the URI [IRI] of external information of interest to maintainers and users of
the schema.
5.5.13 span element
The span element encloses a portion of some paragraph that should be rendered in a distinct way, keyed
with the class attribute.
5.5.14 subject attribute
The subject attribute contains a path allowing more precise specification of nodes. The path expression
is evaluated in the context of the context node of the current rule. If no subject attribute is specified,
the current context node may be used.
NOTE The subject attribute is required becaus
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