Copyright ©2009 XBRL International Inc., All Rights Reserved.
Circulation of this Recommendation is unrestricted. This document is normative. Recipients are invited to submit comments to formula-feedback@xbrl.org, and to submit notification of any relevant patent rights of which they are aware and provide supporting documentation.
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 Relative filters
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 Variables that could support calculation of end-of-period stocks.
2
Variables that could support equity calculation formulae.
This specification is an extension to the XBRL Variables Specification [VARIABLES]. It defines XML syntax [XML] for a filter that supports conditioning upon matching the value of all uncovered aspects of a fact to the corresponding aspects of other facts.
The relative filter identifies a fact variable that aspects are to be matched against. The uncovered aspect values for a fact variable with a relative filter are determined in relation to the uncovered aspect values of the facts matched by the variable identified by the relative filter.
For some variable-sets, relative filtering can provide a finer level of matching control than that available with implicit filtering, as defined in the Implicit filtering specification [IMPLICIT FILTERS].
This specification is a member of a suite of similar specifications that define specific types of criteria that can be used to select facts from XBRL instances. It enhances the fact selection capabilities of the XBRL Variables Specification [VARIABLES].
This specification depends upon the XBRL Specification [XBRL 2.1], and the XBRL Variables Specification [VARIABLES]. In the event of any conflicts between this specification and the specifications upon which it depends, this specification does not prevail.
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.
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 |
|---|---|
rf
|
http://xbrl.org/2008/filter/relative
|
xbrlrfe
|
http://xbrl.org/2008/filter/relative/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
|
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.
A relative filter is declared by an
<rf:relativeFilter>
element.
The syntax for the
<rf:relativeFilter>
element is defined by the normative schema supplied with this specification.
A relative filter covers all or none of the aspects that are not covered by other filters. If a relative filter does cover aspects then the fact variables that it is associated with have no uncovered aspects.
The relative filter can be used to select facts for which the aspects that are covered by the relative filter, have values that match the corresponding aspects of another fact.
The fact that is being matched to by the relative filter MUST be the evaluation result of another fact variable in the variable set being evaluated.
If the fact variable identified by the
@variable attribute on
the relative filter has evaluated to a fallback value
then the implied XPath expression for the relative filter is:
fn:false()
Otherwise the implied XPath expression for the relative filter is obtained as set out below.
The aspects that are matched by a relative filter are determined by the aspect model of the variable set.
The XPath expression implied by a relative filter is constructed as an and-expression from the implied XPath expressions of the matching filters [MATCH FILTERS] that match each of the aspects in the variable set's aspect model that can be covered by the relative filter.
The implied value of the
@variable attribute
for each of the matching filters is equal to the value
of the
@variable attribute on the relative filter.
For aspect models that include
dimension aspects
the implied value of the
@dimension attribute
for each of the dimension matching filters
is equal to the QName of the dimension that is being matched.
Example 1 shows the small number of filters required to define variables that would support stock flow computations. All of the aspects except for the concept, the period and the restatement date typed dimension are matched for the two variables by the relative filter. The relative filter provides an alternative to implicit filtering, as defined in the Implicit filter specification [IMPLICIT FILTERS], for matching the values of many aspects.
| Variables in the variable set | |
|---|---|
| Variable | Filters |
eg:flow
|
|
eg:startingStock
|
|
1.
The use of a non-dimensional aspect model would not be possible for this variable set given the
need to filter based on the eg:restatementDate typed dimension.
Example 2 shows the small number of filters required to define variables that would support computation of equity from total assets and total liabilities. All of the aspects except for the concept, are matched for the two variables by the relative filter. Again the relative filter provides an alternative to implicit filtering, as defined in the Implicit filter specification [IMPLICIT FILTERS], for matching the values of many aspects.
| Variables in the variable set | |
|---|---|
| Variable | Filters |
eg:assets
|
|
eg:liabilities
|
|
1. The use of a non-dimensional aspect model would make this variable set innappropriate for use with XBRL instances that make use of XBRL Dimensions [DIMENSIONS] because matching of segments and scenarios would not take subtleties relating to comparison of XBRL dimension values into account.
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/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/relative-filter.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 |
|---|---|---|
| 18 December 2006 | Geoff Shuetrim |
First internal working draft created, drawing extensively on the previous formula specification drafts |
| 25 April 2007 | Geoff Shuetrim |
Changed the target namespace for the normative schema. |
| 29 May 2007 | Geoff Shuetrim |
Changed the target namespace of the normative schema again. Changed the implied XPath expressions to be consistent with the structures used for the period filters. Changed XPath expression references to $x to #x to be consistent with other filter specifications. Changed the value attribute data types to allow XPath 2.0 expressions rather than constants. |
| 25 June 2007 | Geoff Shuetrim |
Added material to the introduction on the implications of entity filters for implicit filtering. |
| 24 July 2007 | Hugh Wallis |
Edited for public working draft publication. |
| 05 November 2007 | Geoff Shuetrim |
Converted the specification to XML format. Added in the definitions and the hyperlinks to the relevant sections of the normative schema. Added comments about simplifications that should be made. |
| 05 November 2007 | Geoff Shuetrim |
Completed the first draft of the relative filtering specification, reflecting a simplified version of the implicit filtering approach that featured in the second public working draft released in July 2007. Added a dimensional/non-dimensional relative filter distinction to enable relative filtering in a way that is or is not aware of the XBRL Dimensions Specification [DIMENSIONS]. |
| 01 December 2007 | Geoff Shuetrim |
Added examples. Simplified relative filters by ensuring that their aspect models are determined by the aspect model of the variable set that they are being used with. This eliminates the potential for conflicts between the aspect models implied by the relative filter and the aspect model of the variable set. It also ensures that a given variable can be better re-used in two different variable sets that use different aspect models, without distorting the operation of the relative filtering mechanism. |
| 24 January 2008 | Geoff Shuetrim |
Made the |
| 31 January 2008 | Geoff Shuetrim |
Standardised the format of the hyperlinks to the normative schema. |
| 13 March 2008 | Geoff Shuetrim |
Explained the examples better and provided more detail on the relationship to implicit filtering, as suggested by CompSci Resources. |
| 12 August 2008 | Geoff Shuetrim |
Defined the implied XPath expression for the case where the
variable identified by the |
| 27 August 2008 | Geoff Shuetrim |
Collapsed the segment dimension and scenario dimension aspects into the one dimension aspect in line with changes to the dimensional aspect model. |
| 17 November 2008 | Geoff Shuetrim |
Made the |
| 15 December 2008 | Geoff Shuetrim |
Fixed hyperlink formatting problems. |
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.