1 Introduction

One of the most basic requirements in business reporting (e.g.: the reporting of financial statements from a subsidiary to its holding company) is for users of business reports to be able to impose rules on the producers of business reports.

This specification extends the XBRL Validation specification [VALIDATION], defining syntax for assertions about the data that must be in business reports and the data that must not be in business reports.

This assertion about the existence of data in business reports has a similar syntactic structure to the assertion defined in the Value Assertion Specification [VALUE ASSERTIONS]. The main difference is that the context item of the XPath expression in the @test attribute on the assertion is a numeric value that represents the number of different evaluations of the variable set, defined by the assertion, that is expected to be possible for an assertion input.

The result of the assertion is the effective Boolean value of the evaluation of the XPath expression in the test attribute.

This kind of assertion facilitates the definition of business rules that perform checks like those set out in Example 1.

Example 1: Data existence assertions

The report contains exactly one value for total assets.
The report contains at least ten "largest shareholder" tuples.
The report does not contain any facts reported under International Financial Reporting Standards.
The report does not contain any facts that are not reported under International Financial Reporting Standards.

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.

1.1 Background

This specification is a member of a suite of similar specifications that define specific types of assertions that can be tested against the information contained in XBRL business reports.

1.2 Relationship to other work

This specification builds on the foundation provided by the XBRL Validation Specification [VALIDATION].

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
`validation`	`http://xbrl.org/2008/validation`
`ea`	`http://xbrl.org/2008/assertion/existence`
`xbrleae`	`http://xbrl.org/2008/assertion/existence/error`
`eg`	`http://example.com/`
`fn`	`http://www.w3.org/2005/xpath-functions`
`link`	`http://www.xbrl.org/2003/linkbase`
`xbrli`	`http://www.xbrl.org/2003/instance`
`xfi`	`http://www.xbrl.org/2008/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`
`gen`	`http://xbrl.org/2008/generic`
`variable`	`http://xbrl.org/2008/variable`
`iso4217`	`http://www.xbrl.org/2003/iso4217`

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 Existence assertions

An existence assertion is a statement about the number of times that the assertion's variable set will evaluate against a input XBRL instance.

An existence assertion is expressed by the <ea:existenceAssertion> element in the normative schema supplied with this specification.

If an existence assertion contains a @test attribute, the existence-assertion expression is the XPath expression contained by that attribute. If the @test attribute is omitted from the existence assertion, then the existence-assertion expression is equal to the context item expression^{[
1
]}.

The assertion expression MAY have variable dependencies on parameters in the variable-set, but MUST NOT have dependencies on general variables or fact variables.

Error code xbrleae:variableReferenceNotAllowed MUST be thrown if the existence-assertion expression has a variable dependency on a general variable or a fact variable.

2.2 Relationships involving existence assertions

Existence assertions are in the substitution group for the <validation:variableSetAssertion> element, and so, can be starting resources for those relationships that are required to have a variable-set as starting resource.

3 The processing model for existence assertions

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

An existence assertion evaluation involves evaluation of the existence-assertion expression using an evaluation context where the context item has an atomic value equal to the cardinality of the set of all possible different evaluations of the assertion's variable-set.

In-scope variables MUST include all variable parameters associated to the assertion, but MUST NOT include any fact variable or general variable.

Example 2: Existence assertion expressions

`@test` attribute value	Number of evaluations of the variable set for the assertion being verified
omitted	At least one evaluation
`.`	At least one evaluation
`. gt 5`	At least six evaluations
`. eq 0`	No evaluations
`. ge $numberOfItems`	Equal to or greater than the number provided in the parameter identified by the variable name $numberOfItems

Existence assertions produce at most one evaluation for a given assertion input. This is because the existence assertion test is related to the total number of evaluations of the variable set of the assertion as a whole. Thus, the data set of an existence assertion is the entire assertion input.

An existence assertion MAY be evaluated for any valid assertion input. Testing of an existence assertion requires all possible different evaluations of the assertion's variable set to be performed to determine the context item for the existence assertion expression.

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:

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 http://www.xbrl.org/2008/ - 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/2008/existence-assertion.xsd.
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.

</extension>

</complexContent>

</complexType>

</element>

</schema>

Appendix B References

CONSISTENCY ASSERTIONS: XBRL International Inc.. "XBRL Value Assertions 1.0"
Victor Morilla, and Geoff Shuetrim.
(See ../../consistencyAssertions/REC-2009-06-22/consistencyAssertions-REC-2009-06-22.html)
IETF RFC 2119: IETF (Internet Engineering Task Force). "RFC 2119: Key words for use in RFCs to Indicate Requirement Levels"
Scott Bradner.
(See http://www.ietf.org/rfc/rfc2119.txt)
VALIDATION: XBRL International Inc.. "XBRL Validation 1.0"
Victor Morilla, and Geoff Shuetrim.
(See ../../validation/REC-2009-06-22/validation-REC-2009-06-22.html)
VALUE ASSERTIONS: XBRL International Inc.. "XBRL Value Assertions 1.0"
Victor Morilla, and Geoff Shuetrim.
(See ../../valueAssertions/REC-2009-06-22/valueAssertions-REC-2009-06-22.html)
VARIABLES: 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)
XML NAMES: W3C (World Wide Web Consortium). "Namespaces in XML 1.0 (Second Edition)"
Tim Bray, Dave Hollander, Andrew Layman, and Richard Tobin.
(See http://www.w3.org/TR/REC-xml-names/)
XML SCHEMA STRUCTURES: W3C (World Wide Web Consortium). "XML Schema Part 1: Structures Second Edition"
Henry S. Thompson, David Beech, Murray Maloney, and Noah Mendelsohn.
(See http://www.w3.org/TR/xmlschema-1/)
XPATH 2.0: W3C (World Wide Web Consortium). "XML Path Language (XPath) 2.0"
Anders Berglund, Scott Boag, Don Chamberlin, Mary F. Fernández, Michael Kay, Jonathan Robie, and Jérôme Siméon.
(See http://www.w3.org/TR/xpath20/)

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 (www.xbrl.org/legal).

This document and the information contained herein is provided on an "AS IS" basis and XBRL INTERNATIONAL DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

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).

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)

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.
24 November 2007	Victor Morilla	Split from validation report specification Adapted to reuse variable sets and preconditions
26 November 2007	Geoff Shuetrim	Minor wording edits.
30 November 2007	Victor Morilla	Adapted to new version of variables specification. Included section for processing model and added errors.
04 December 2007	Geoff Shuetrim	Reworded some paragraphs. Moved some definitions to the variable specification relating to identical and different variable-set evaluations.
04 December 2007	Victor Morilla	Removed agreed comments and paragraph about the consideration of preconditions and groupfilters as suggested by Geoff
06 December 2007	Victor Morilla	References to the definition of the assertion data set
16 December 2007	Victor Morilla	Changed namespace of existence assertions from http://xbrl.org/2008/existence-assertion to http://xbrl.org/2008/assertion/existence
29 January 2008	Victor Morilla	Removed constraint on the number of fact variables of existence assertions and its corresponding error as suggested by Herm Fischer.
31 January 2008	Geoff Shuetrim	Standardised the format of the hyperlinks to the normative schema. Standardised the boilerplate text for errata.
04 February 2008	Geoff Shuetrim	Corrected the element name for the existence assertion in the text of the specification. Corrected the caption for the first example. It used to refer to dimension filters instead of existence assertion expressions.
06 February 2008	Victor Morilla	Editorial changes suggested by Geoff Shuetrim. Merged "test implied" and "processing model" chapters. Clarified in-scope variables of the existence assertion expression. Simplified redundant paragraph about variable-set relationships.
13 March 2008	Geoff Shuetrim	Added mention of the limited ability to use consistency assertions to test for fact existence to the abstract as suggested by CompSci Resources.
19 March 2009	Geoff 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.

End Notes

[1]: Given the definition of the processing model for existence assertions, the context item expression is equal to the cardinality of the set of all possible different evaluations of the assertion's variable-set

Existence Assertions 1.0

Recommendation 22 June 2009

Status

Abstract

Table of Contents

Appendices

Table

Examples

Definitions

Error code