Validation 1.0

Recommendation 22 June 2009

Copyright ©2009 XBRL International Inc., All Rights Reserved.

This version:
Victor Morilla, Banco de España <>
Geoff Shuetrim, Galexy <>
Paul Bull, Morgan Stanley <>
Herm Fischer, UBMatrix / Mark V Systems <>
Masatomo Goto, Fujitsu <>
Roland Hommes, Rhocon / Consultant to Netherlands Tax and Customs Administration <>
Takahide Muramoto, Fujitsu <>
Jim Richards, JDR & Associates <>
Michele Romanelli, Banca d'Italia <>


Circulation of this Recommendation is unrestricted. This document is normative. Recipients are invited to submit comments to, and to submit notification of any relevant patent rights of which they are aware and provide supporting documentation.


This document describes an extension to the XBRL 2.1 specification [XBRL 2.1] that builds upon the XBRL formula specification [FORMULA] and XBRL variable specification [VARIABLES] to provide the base syntax for expression of assertions that may be tested against the content of XBRL reports. This specification does not define any specific assertion, but provides a set of common definitions, resources and relationships that serve as a common foundation for XBRL assertion specifications.

Table of Contents

1 Introduction
1.1 Background
1.2 Relationship to other work
1.3 Language independence
1.4 Terminology
1.5 Document conventions (non-normative)
1.6 Namespaces and namespace prefixes
1.7 XPath usage
2 Syntax
2.1 Assertions
2.2 Assertion relationships
2.3 Assertion sets
2.3.1 Assertion-set relationships
3 The processing model for all assertions


A Normative schema
B References
C Intellectual property status (non-normative)
D Acknowledgements (non-normative)
E Document history (non-normative)
F Errata corrections in this document


1 Namespaces and namespace prefixes


1 Typical existence assertions
2 Typical value assertions
3 Typical consistency assertions


assertion data set
assertion evaluation
assertion evaluation is not satisfied
assertion evaluation is satisfied
assertion input
assertion set
assertion test
assertion-set relationship
rfc2119 terminology

1 Introduction

An important feature of XBRL is its ability to declare not only business concepts definitions, but also rules that constrain the information in business reports. For instance:

Such constraints can improve the quality of data in business reporting environments. However, the validations that can be expressed using the XBRL Specification [XBRL 2.1] and XBRL Dimensions Specification [DIMENSIONS] do not address the kinds of complex business rules that are common in regulatory contexts such as prudential reporting.

This document specifies the base XML syntax [XML] for such business rules. Each business rule takes the form of an assertion about one or more properties of an XBRL instance. Validation of an XBRL instance against a set of business rules involves testing that instance against a set of assertions about it. Some assertions are simple statements that an instance should or should not contain facts with a specified set of properties. For example:

Example 1: Typical existence assertions
  • Instances contain facts reporting values for total assets.
  • Instances contain facts that describe entities with identifiers that belong to a specific entity identification scheme.
  • Instances do not include facts with a duration period that ends after a specific cut-off date.

A second category of assertions can be expressed as restrictions on the allowed values of facts in an XBRL instance.

Example 2: Typical value assertions
  • The capital adequacy ratio exceeds eight percent.
  • The interest cover ratio exceeds 2.5.
  • The cash balance is positive.

Other types of assertions can be expressed as mathematical relationships that are expected to hold in XBRL instances. Such assertions involve a functional relationship mapping a set of inputs to an expected output. For example:

Example 3: Typical consistency assertions
  • The balance sheet balances, implying that total assets is equal to the sum of total liabilities plus total equity.
  • The difference between a starting balance and an ending balance is equal to the flows during the intervening period.

Validation of an XBRL instance involves: choosing an assertion set, optionally specifying values for some parameters, and then testing the assertions in the assertion set against the data in the XBRL instance.

An XBRL instance can contain more than one data set for which a given assertion can be tested. The "balance sheet must balance" assertion, for example, could be tested against balance sheets reported for multiple financial years and for multiple reporting entities, all within the one XBRL instance.

When tested against a data set in an XBRL instance, an assertion returns true if the assertion is found to hold and false otherwise.

This specification defines syntax for expressing assertions and their relationships to other data structures in XLink extended links [XLINK]. The syntax for specific assertions is expressed in separate specifications that leverage both the XBRL Variables Specification [VARIABLES] and the XBRL Formulae Specification [FORMULA]. Assertions are documented using generic labels [GENERIC LABELS] and generic references [GENERIC REFERENCES].

Many of the syntax constraints imposed by this specification are enforced by the normative schema Appendix A. To eliminate the potential for conflicts, this specification only enunciates requirements that are not enforced by the normative schema.

1.1 Background

This specification is intended to be augmented by separate assertion specifications that define the syntax for different kinds of assertions that can be tested against data in XBRL instances.

1.2 Relationship to other work

This specification builds on the foundation provided by the XBRL Formula Specification [FORMULA] and the XBRL Variables Specification [VARIABLES].

1.3 Language independence

The official language of XBRL International's own work products is English and the preferred spelling convention is UK English.

1.4 Terminology

This specification is consistent with the definitions of any of the terms defined in specifications that it depends on.

The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, in this specification, are to be interpreted as described in [IETF RFC 2119].

1.5 Document conventions (non-normative)

Documentation conventions follow those set out in the XBRL Variables Specification [VARIABLES].

1.6 Namespaces and namespace prefixes

Namespace prefixes [XML NAMES] will be used for elements and attributes in the form ns:name where ns is the namespace prefix and name is the local name. Throughout this specification, the mappings from namespace prefixes to actual namespaces is consistent with Table 1.

The prefix column in Table 1 is non normative. The namespace URI column is normative.

Table 1: Namespaces and namespace prefixes
Prefix Namespace URI

1.7 XPath usage

XPath usage is identical to that in the XBRL Variables Specification [VARIABLES].

2 Syntax

This specification only provides a textual declaration of syntax constraints when those constraints are not expressed by the normative schema supplied with this specification.

Explanations of elements and attributes are only supplied when explanations are not already provided in other specifications.

Unless explicitly stated otherwise, a reference to a specific element MUST be read as a reference to that element or to any element in its substitution group.

2.1 Assertions

An assertion is a testable statement about the content of an XBRL instance and the parameter values supplied along with that XBRL instance.

Assertions are expressed by XLink resources in XLink extended links.

All assertions MUST be in the substitution group for the <validation:assertion> element or the <validation:variableSetAssertion> element.

2.2 Assertion relationships

Because assertions that are in the substitution group for the <validation:variableSetAssertion> element, they are also in the substitution group for the <variable:variableSet> element. As a consequence, such assertions can be starting resources for those relationships that are required to have a variable-set as starting resource.

The following relationships are subject to this requirement:

Assertion specifications MAY define new relationships with other resources.

2.3 Assertion sets

An assertion set is an resource expressed by the <validation:assertionSet> element.

Assertion sets serve to define groupings of assertions.

2.3.1 Assertion-set relationships

If an assertion is part of the set of assertions defined by an assertion set then it MUST have an assertion-set relationship to the assertion set.

An assertion-set relationship is a relationship between an assertion-set and an assertion that is expressed by an XLink arc.

To declare an assertion-set relationship an XLink arc MUST:

The arcrole value,, is declared in the normative schema supplied with this spcification.

Assertion-set relationships MUST be expressed by generic arcs as indicated by the restrictions imposed by the arcrole declaration in the normative schema. Violations of this requirement will be detected by validation against the XBRL Specification [XBRL 2.1].

3 The processing model for all assertions

This section defines key features of the processing model for all assertions. Assertion specifications may augment these key features of the processing model.

All assertions are tested against an assertion input.

An assertion input, is a input XBRL instance and the values of the parameters supplied with that input XBRL instance.

An assertion data set is a subset of information in or derived from the assertion input that can be tested against an assertion.

An assertion evaluation is the result produced by testing an assertion against an assertion data set

An assertion input can contain more than one assertion data set for a given assertion. Given an assertion input, an assertion MAY be evaluated once for each assertion data set in the assertion input.

An assertion test is the effective Boolean value produced by an assertion evaluation.

An assertion evaluation is satisfied when its assertion test equals true.

An assertion evaluation is not satisfied when its assertion test equals false.

Assertion specifications MUST define the assertion data sets for the assertions being specified.

Assertion specifications MUST also specify how the assertions being defined are to be evaluated using the assertion data sets to produce assertion tests.

Appendix A Normative schema

The following is the XML schema provided as part of this specification. This is normative. Non-normative versions (which should be identical to these except for appropriate comments indicating their non-normative status) are also provided as separate files for convenience of users of the specification.

NOTE: (non-normative) Following the schema maintenance policy of XBRL International, it is the intent (but is not guaranteed) that the location of non-normative versions of these schemas on the web will be as follows:

  1. While any schema is the most current RECOMMENDED version and until it is superseded by any additional errata corrections a non-normative version will reside on the web in the directory - during the drafting process for this specification this directory should contain a copy of the most recent published version of the schema at
  2. A non-normative version of each schema as corrected by any update to the RECOMMENDATION will be archived in perpetuity on the web in a directory that will contain a unique identification indicating the date of the update.
<schema xmlns:validation="" xmlns:variable="" xmlns="" xmlns:gen="" xmlns:link="" targetNamespace="" elementFormDefault="qualified">
<import namespace="" schemaLocation=""/>
<import namespace="" schemaLocation="variable.xsd"/>
<!-- arcrole from an assertionSet resource to an assertion resource -->
<link:arcroleType id="assertion-set" cyclesAllowed="undirected" arcroleURI="">
assertion set contains assertion
<!-- Assertion resource abstract elements definition -->
<element id="xml-abstract-assertion" name="assertion" abstract="true" type="validation:assertion.type" substitutionGroup="variable:resource"/>
<complexType name="assertion.type">
<complexContent mixed="true">
<extension base="variable:resource.type"/>
<element id="xml-abstract-variable-set-assertion" name="variableSetAssertion" abstract="true" type="validation:assertion.variableSet.type" substitutionGroup="variable:variableSet"/>
<complexType name="assertion.variableSet.type">
<complexContent mixed="true">
<extension base="variable:variableSet.type"/>
<!-- Assertion set element definition -->
<element id="xml-assertion-set" name="assertionSet" type="validation:assertionSet.type" substitutionGroup="variable:resource"/>
<complexType name="assertionSet.type">
<complexContent mixed="true">
<extension base="variable:resource.type"/>

Appendix B References

XBRL International Inc.. "XBRL Dimensions 1.0"
Ignacio Hernández-Ros, and Hugh Wallis.
XBRL International Inc.. "XBRL Formulae 1.0"
Phillip Engel, Herm Fischer, Victor Morilla, Jim Richards, Geoff Shuetrim, David vun Kannon, and Hugh Wallis.
(See ../../formula/CR-2008-12-31/formula-CR-2008-12-31.html)
XBRL International Inc.. "XBRL Generic Labels 1.0"
Phillip Engel, Herm Fischer, Victor Morilla, Jim Richards, Geoff Shuetrim, David vun Kannon, and Hugh Wallis.
(See ../../genericLabels/REC-2009-06-22/genericLabels-REC-2009-06-22.html)
XBRL International Inc.. "XBRL Generic Links 1.0"
Mark Goodhand, Ignacio Hernández-Ros, and Geoff Shuetrim.
(See ../../gnl/REC-2009-06-22/gnl-REC-2009-06-22.html)
XBRL International Inc.. "XBRL Generic References 1.0 (Public Working Draft)"
Phillip Engel, Herm Fischer, Victor Morilla, Jim Richards, Geoff Shuetrim, David vun Kannon, and Hugh Wallis.
(See ../../genericReferences/REC-2009-06-22/genericReferences-REC-2009-06-22.html)
IETF (Internet Engineering Task Force). "RFC 2119: Key words for use in RFCs to Indicate Requirement Levels"
Scott Bradner.
XBRL International Inc.. "XBRL Variables 1.0"
Phillip Engel, Herm Fischer, Victor Morilla, Jim Richards, Geoff Shuetrim, David vun Kannon, and Hugh Wallis.
(See ../../variables/REC-2009-06-22/variables-REC-2009-06-22.html)
XBRL 2.1
XBRL International Inc.. "Extensible Business Reporting Language (XBRL) 2.1"
Phillip Engel, Walter Hamscher, Geoff Shuetrim, David vun Kannon, and Hugh Wallis.
W3C (World Wide Web Consortium). "XML Linking Language (XLink) Version 1.0"
Steve DeRose, Eve Maler, and David Orchard.
W3C (World Wide Web Consortium). "Extensible Markup Language (XML) 1.0 (Fourth Edition)"
Tim Bray, Jean Paoli, C. M. Sperberg-McQueen, Eve Maler, and François Yergeau.
W3C (World Wide Web Consortium). "Namespaces in XML 1.0 (Second Edition)"
Tim Bray, Dave Hollander, Andrew Layman, and Richard Tobin.
W3C (World Wide Web Consortium). "XML Schema Part 1: Structures Second Edition"
Henry S. Thompson, David Beech, Murray Maloney, and Noah Mendelsohn.

Appendix C Intellectual property status (non-normative)

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 XBRL International or XBRL organizations, except as required to translate it into languages other than English. Members of XBRL International agree to grant certain licenses under the XBRL International Intellectual Property Policy (


The attention of users of this document is directed to the possibility that compliance with or adoption of XBRL International specifications may require use of an invention covered by patent rights. XBRL International shall not be responsible for identifying patents for which a license may be required by any XBRL International specification, or for conducting legal inquiries into the legal validity or scope of those patents that are brought to its attention. XBRL International specifications are prospective and advisory only. Prospective users are responsible for protecting themselves against liability for infringement of patents. XBRL International takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Members of XBRL International agree to grant certain licenses under the XBRL International Intellectual Property Policy (

Appendix D Acknowledgements (non-normative)

This document could not have been written without the contributions of many people including the participants in the Formula Working Group.

Appendix E Document history (non-normative)

30 June 2007Geoff Shuetrim

Initial draft created.

22 July 2007Geoff Shuetrim

Converted to XML format.

15 October 2007Geoff Shuetrim

Adapted to XBRLspec syntax.

18 November 2007Victor Morilla

Created initial draft of validation specification from contents of validation-report specification by Geoff Shuetrim.

18 November 2007Victor Morilla

Removed references to variable set resources. Included proposal of relationships for preconditions and group filters

26 November 2007Geoff Shuetrim

Fixed up typographic errors. Added comments and responses to questions. Added a formal definition of an assertion set.

26 November 2007Geoff Shuetrim

Fixed up typographic errors. Added comments and responses to questions. Added a formal definition of an assertion set.

30 November 2007Victor Morilla

Adapted to new variable specification. Included Geoff's comments.

04 December 2007Victor Morilla

Included hint about usage of assertion-sets.

Removed obsolete comments

Moved assertion-formula relationship to consistency-assertion spec

06 December 2007Victor Morilla

Recovered the definition of the assertion data set

Removed obsolete comments

09 December 2007Victor Morilla

Removed the validationArc in favour of generic arcs.

assertion-set relationships now used on generic arcs.

10 December 2007Victor Morilla

Included two abstract elements for assertions; one in the substitution group for variable:resource and another one in the substitution group for variable:variableSet. Those assertions that determine a variable-set (value and existence) must be in the substitution group for the latter; others (consistency assertions) must be in the substitution group for the former.

31 January 2008Geoff Shuetrim

Standardised the format of the hyperlinks to the normative schema.

Standardised the boilerplate text for errata.

03 February 2008Geoff Shuetrim

Revised the abstract to simplify the wording and to provide links to the underpinning specifications.

04 February 2008Geoff Shuetrim

Corrected a range of minor grammatical problems in the text of the the specification and clarified a number of definitions. Moved the paragraphs on data sets from the syntax section to the processing model section.

04 February 2008Geoff Shuetrim

Made small clarifications to the wording of the processing model documentation.

09 April 2008Geoff Shuetrim

Corrected typos in the definition of an assertion as identified by Takahide Muramoto.

13 August 2008Geoff Shuetrim

Removed un-necessary schema limitations on undirected cycles in relationship networks.

15 December 2008Geoff Shuetrim

Updated references to the latest errata-corrected version of the XBRL 2.1 specification.

19 March 2009Geoff Shuetrim

Changed the term "target XBRL instance" to "input XBRL instance". Ensured that all usages of the terms input XBRL instance and output XBRL instance reference the term definition.

Appendix F Errata corrections in this document

This appendix contains a list of the errata that have been incorporated into this document. This represents all those errata corrections that have been approved by the XBRL International Formula Working Group up to and including 22 June 2009. Hyperlinks to relevant e-mail threads may only be followed by those who have access to the relevant mailing lists. Access to internal XBRL mailing lists is restricted to members of XBRL International Inc.

No errata have been incorporated into this document.