Copyright ©2007 XBRL International Inc., All Rights Reserved.
Circulation of this Public Working Draft is unrestricted. This document is normative. Other documents may supersede this document. Recipients are invited to submit comments to the authors and contributors, and to submit notification of any relevant patent rights of which they are aware and to provide supporting documentation.
This document describes an extension to the XBRL 2.1 specification that builds upon the XBRL formula and XBRL variable specifications to provide the base syntax for expressing validation rules, so called assertions, that may be tested on the content of XBRL reports. This specification does not define any specific assertion, but a set of common definitions, resources and relationships on top of which other extensions are built.
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 assertions
4 Message reporting
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
assertion data set
assertion evaluation
assertion evaluation not satisfied
assertion evaluation satisfied
assertion input
assertion set
assertion test
assertion-set relationship
rfc2119 terminology
An important feature of XBRL is its ability to declare not only business concepts definitions, but rules to constrain the information provided by business reports. For instance:
Such constraints can improve the quality of data in business reporting environments. However, the validations that are possible using the XBRL Specification [XBRL 2.1] and XBRL Dimensions Specification [DIMENSIONS] still do not address the complex business rules that are common in regulatory contexts such as prudential reporting and many others.
This document specifies the base XML syntax [XML] for such business rules. Each business rule takes the form of an assertion about some 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 its content. Some assertions are simple statements that an instance should or should not contain facts with a specified set of properties. For example:
A second category of assertions can be expressed as restrictions on the allowed values of facts in an XBRL instance.
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:
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 always returns true if the assertion is found to hold and false otherwise.
This specification defines syntax and common conventions for expressing assertion local resources and relationships in extended links [XLINK]. The content of assertions is expressed on separate specifications using variables [VARIABLES] and formulae [FORMULA]. Assertion documentation is provided by generic labels [GENERIC LABELS] and generic references [GENERIC REFERENCES].
The definition of specific categories of assertions is provided in different specifications. This way, the XBRL Validation specification is flexible and open to the addition of new kinds of assertions in a future as new requirements are included.
Many of the syntax constraints imposed by this specification are set out in the normative schema Appendix A. To eliminate the potential for conflicts, this specification only enunciates syntax features that are not expressed in the normative schema.
This specification is intended to be augmented with a range of separate assertion specifications that provide specific syntax for different kinds of assertions that can be tested against data in XBRL instances.
This specification builds on the foundation provided by the [FORMULA] and [VARIABLES] specifications.
The official language of XBRL International's own work products is English and the preferred spelling convention is UK English.
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].
Documentation conventions follow those set out in the XBRL Variables Specification [VARIABLES].
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.
| Prefix | Namespace URI |
|---|---|
validation
|
http://xbrl.org/2007/validation
|
xbrlvalide
|
http://xbrl.org/2007/validation/error
|
eg
|
http://example.com/
|
fn
|
http://www.w3.org/2006/xpath-functions
|
link
|
http://www.xbrl.org/2003/linkbase
|
xbrli
|
http://www.xbrl.org/2003/instance
|
xfi
|
http://www.xbrl.org/2005/function/instance
|
xbrldi
|
http://xbrl.org/2006/xbrldi
|
xbrldt
|
http://xbrl.org/2005/xbrldt
|
xl
|
http://www.xbrl.org/2003/XLink
|
xlink
|
http://www.w3.org/1999/xlink
|
xs
|
http://www.w3.org/2001/XMLSchema
|
xsi
|
http://www.w3.org/2001/XMLSchema-instance
|
generic
|
http://xbrl.org/2007/generic
|
variable
|
http://xbrl.org/2007/variable
|
iso4217
|
http://www.xbrl.org/2003/iso4217
|
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 .
An assertion is a Boolean statement that can be tested on the content of an XBRL instance.
Assertions are declared as
XLink resources in
XLink extended links.
Specific assertion resources MUST be in the
substitution group
for the abstract
<validation:assertion> element
or the abstract
<validation:variableSetAssertion> element.
The latter are in the
substitution group for
variable
sets as well.
An assertion evaluation is the result produced by an assertion when applied to a data set
An XBRL instance can contain more than one data set for which a given assertion can be tested, and thus, produce more than one evaluation of the same assertion.
An assertion evaluation is said to be satisfied when its result is true.
An assertion evaluation is said to be not satisfied when its result is false.
Assertions that belong to the
substitution group for the
<validation:variableSetAssertion> element,
belong to the
substitution group for
variable-sets.
As a consequence,
such assertions can be used as a starting resource for
those relationships that have a
variable-set as starting resource of the arc:
Specific assertion categories define how this relationships are used and MAY define new relationships with other resources.
An assertion set is expressed by the <validation:assertionSet> element.
An assertion MAY be part of an assertion set. The relationships between an assertion and the assertion sets that it is part of are defined by Xlink arcs that:
An assertion-set relationship is a relationship between an assertion-set and a assertion expressed by an XLink arc.
To declare an assertion-set relationship an XLink arc MUST:
http://xbrl.org/arcrole/2007/assertion-set
The arcrole value,
http://xbrl.org/arcrole/2007/assertion-set,
is declared in
the normative schema
for dimension filters.
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].
Such relationships are referred to as assertion-set relationships.
This section defines general terms of the processing model for assertions. Specific categories of assertions may refine this model.
The input to an assertion, referred to as the assertion input, is the target XBRL instance and values supplied by the processing application for any of the parameters that an assertion is dependent on.
Given an assertion input, an assertion MAY produce one, more than one, or no evaluations: one result for each data set.
Some assertions test a condition on a certain variable set; this kind of assertions MAY produce an evaluation for each variable-set evaluation. Other assertions test a condition based upon one or more than one formulae; this kind of assertions MAY produce an evaluation for each output fact produced by these formulae. Other assertions test a global condition against the target XBRL instance; this kind of assertion produces just one evaluation.
The processing model is defined for a single evaluation of a single assertion. An evaluation of an assertion depends on the determination of a data set. This step is defined by the specific category of the assertion being evaluated.
Given the determination of the data set, the assertion evaluation entails evaluating the test implied by the assertion.
A broad range of information can be usefully provided by an assertion capable formula processor.
Such information includes:
The format and content of the messages generated by such processors are out of the scope of this specification and thus, are application dependent.
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:
http://www.xbrl.org/2007/ - during the drafting process for
this specification this directory should contain a copy of the
most recent published version of the schema at
http://www.xbrl.org/2007/validation.xsd.
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 (www.xbrl.org/legal).
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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 (www.xbrl.org/legal).
This document could not have been written without the contributions of many people including the participants in the Formula Working Group.
| Date | Author | Details |
|---|---|---|
| 30 June 2007 | Geoff Shuetrim |
Initial draft created. |
| 22 July 2007 | Geoff Shuetrim |
Converted to XML format. |
| 15 October 2007 | Geoff Shuetrim |
Adapted to XBRLspec syntax. |
| 18 November 2007 | Victor Morilla |
Created initial draft of validation specification from contents of validation-report specification by Geoff Shuetrim. |
| 18 November 2007 | Victor Morilla |
Removed references to variable set resources. Included proposal of relationships for preconditions and group filters |
| 26 November 2007 | Geoff Shuetrim |
Fixed up typographic errors. Added comments and responses to questions. Added a formal definition of an assertion set. |
| 26 November 2007 | Geoff Shuetrim |
Fixed up typographic errors. Added comments and responses to questions. Added a formal definition of an assertion set. |
| 30 November 2007 | Victor Morilla |
Adapted to new variable specification. Included Geoff's comments. |
| 04 December 2007 | Victor Morilla |
Included hint about usage of assertion-sets. Removed obsolete comments Moved assertion-formula relationship to consistency-assertion spec |
| 06 December 2007 | Victor Morilla |
Recovered the definition of the assertion data set Removed obsolete comments |
| 09 December 2007 | Victor Morilla |
Removed the validationArc in favour of generic:arc assertion-set relationships now used on generic:arc |
| 10 December 2007 | Victor 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. |
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 31 December 2007 . 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.