XBRL Unit Filters Specification 1.0
Public Working Draft, dated 2007-07-13
Copyright © 2006, XBRL International Inc., All Rights Reserved
This version:
Unit-Filters-PWD-2007-07-13.rtf
is NORMATIVE. All other versions and formats are non-normative.
Editors
Name	Contact	Affiliation	
Phillip Engel	phillip.engel@morganstanley.com 	Morgan Stanley	
Geoff Shuetrim	geoff@galexy.net	Galexy	
David vun Kannon	david.k.vunkannon@us.pwc.com 	PricewaterhouseCoopers LLP	
Hugh Wallis	hughwallis@xbrl.org	XBRL International	
Contributors
			
Abstract
This specification is an extension to the XBRL Variables 1.0 Specification [VARIABLES].  It specifies syntax for filters that can be used to ensure that a variable only binds to facts meeting specified criteria in relation to their units of measure.
Status
This is a Public Working Draft whose circulation is unrestricted. Comments should be directed to the editor and/or contributors by e-mail.  Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation.
In the final version of this document:
•	relevant schema extracts will be included in the text of the specification
•	relevant examples will be included
•	error codes will be included.
To reduce the editorial burden, these aspects of the specification have been omitted for internal working drafts.
Normative status
This document is normative in the sense that any implementing processor must obey the rules described within it, in order to be considered a conformant processor.

Table of contents
1.1	Document conventions (non-normative)
1.1.1	Typographic conventions
1.1.2	Formatting conventions
1.1.3	Namespace conventions (normative)
1.2	Relationship to other work
1.3	Language independence
1.4	Terminology
1.5	XPath usage
2	Introduction
3	Syntax
3.1	Specific unit filter declarations
3.2	General unit filter declarations
Appendices
A	References (non-normative)
B	Normative schema
C	Intellectual Property Status (non-normative)
D	Acknowledgements (non-normative)
E	Document History (non-normative)
F	Approval process (non-normative)

1.1	Document conventions (non-normative)
1.1.1	Typographic conventions
Comments which are informative, but not essential to the understanding of the point at hand are provided in footnotes. All footnotes are non-normative.
1.1.2	Formatting conventions
The following highlighting is used to present normative technical material in this document:
	
The following formatting is used for non-normative examples in this document:

The following formatting is used for non-normative counterexamples (examples of poor, discouraged or disallowed usage) in this document:

1.1.3	Namespace conventions (normative)
This table contains all the prefixes used within the text and the correspondent namespace URI. The prefix column in the table above is non normative. The namespace URI column is normative.
Prefix	Namespace URI	
xbrli	http://www.xbrl.org/2003/instance	
xs	http://www.w3.org/2001/XMLSchema	
xfi	http://www.xbrl.org/2005/function/instance	
fn	http://www.w3.org/2006/xpath-functions	
xlink	http://www.w3.org/1999/xlink	
link	http://www.xbrl.org/2003/linkbase	
xl	http://www.xbrl.org/2003/XLink	
generic	http://xbrl.org/2007/generic	
bind	http://xbrl.org/2007/bind	
filter	http://xbrl.org/2007/filter/unit	
1.2	Relationship to other work
This specification depends upon XBRL 2.1 Specification [XBRL]. This specification depends upon XBRL Variables 1.0 Specification [VARIABLES].
In the event of any conflicts between this specification and the specifications upon which it depends, this specification does not prevail.
This specification has dependencies on specific XBRL functions [XBRLFunc] that will need to be defined.
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
All terminology defined in the XBRL 2.1 Specification is used unchanged in this specification.
The following additional terms are used as described in the table below:
Term	Meaning (Normative)	
specific unit filter	A specific unit filter defines a test of a fact against a unit defined in terms of a single measure.	
general unit filter	A general unit filter enables definition of a test of a fact against a general representation of a unit.	
1.5	XPath usage
XPath usage is identical to that in the XBRL Formula 1.0 Specification [FORMULA].
2	Introduction
This specification provides syntax for filters that can be used to ensure that a variable only binds to facts meeting specified criteria in relation to their units of measure.
In relation to implicit filtering, as defined in the XBRL Variables Specification [VARIABLES], all filters defined in this specification cover the unit aspect of facts.
3	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 those explanations are not already provided in other specifications.
Where the value of an attribute is to be inserted into an XPath expression to define the XPath expression implied by a filter, that value will be referred to in the XPath expression using a # sign followed by the name of the attribute.  For example, if a filter provides an attribute called “namespace” and an attribute called name and they are to be inserted into an XPath expression, the representation of the XPath expression in this specification might be:
count(xfi:unit-numerator(.))=1 and 
xfi:measure-name(xfi:unit-numerator(.)[1])= fn:QName('#namespace','#name')
3.1	Specific unit filter declarations
Sometimes, it is useful to filter facts based upon a single unit of measure.  The filter:singleMeasure element supports such filtrations.  It is referred to as a single measure unit filter.
The syntax for the single measure unit filter is defined by the normative schema supplied with this specification.
The XPath expression implied by a single measure unit filter is constructed as follows:
xfi:is-numeric(.) and
count(xfi:unit-numerator(.))=1 and 
count(xfi:unit-denominator(.))=0 and 
xfi:measure-name(xfi:unit-numerator(.)[1])= #dimension
#dimension is the value of the filter:qnameExpression element if it is contained by the filter and #dimension is given by xs:QName(#namespace, #name) if the filter:qname element is contained by the filter.  #namespace is the namespace for the QName specified as the content of the filter:qname element and #name is the local name for the QName specified as the content of the filter:qname element.
3.2	General unit filter declarations
Sometimes, it is useful to filter facts based upon a unit of measure that involves several measures.  The filter:generalMeasures element supports such filtrations.  It is referred to as a general unit filter.
The syntax for the general unit filter is defined by the normative schema supplied with this specification.
The XPath expression implied by a general unit filter is constructed as follows:
xfi:is-numeric(.) and
xfi:unit(.)[$test]

Appendices
A	References (non-normative)
[FORMULA]	Phillip Engel, Geoff Shuetrim, David vun Kannon, Hugh Wallis (editors)
XBRL Formula Specification 1.0 Public Working Draft
http://www.xbrl.org/SpecPWDs/ 	
[VARIABLES]	Phillip Engel, Geoff Shuetrim, David vun Kannon, Hugh Wallis (editors)
XBRL Variables 1.0 Specification, Public Working Draft
http://www.xbrl.org/SpecPWDs/	
[XBRL]	Phillip Engel, Walter Hamscher, Geoff Shuetrim, David vun Kannon and Hugh Wallis
Extensible Business Reporting Language 2.1 Recommendation 
http://www.xbrl.org/SpecRecommendations/	
[XBRLFunc]	Chris Simmons (editor), Cliff Binstock, Phillip Engel, Herm Fischer, David vun Kannon, Hugh Wallis and Paul Warren
XBRL Functions 1.0 Public Working Draft
http://www.xbrl.org/SpecPWDs/	
B	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 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/unit-filter.xsd.
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. 

<?xml version="1.0" encoding="UTF-8"?>
<!-- Copyright 2007 XBRL International. All Rights Reserved. -->
<schema 
  targetNamespace="http://xbrl.org/2007/filter/unit"
  xmlns:uf="http://xbrl.org/2007/filter/unit" 
  xmlns:expression="http://xbrl.org/2007/expression" 
  xmlns:link="http://www.xbrl.org/2003/linkbase" 
  xmlns:xl="http://www.xbrl.org/2003/XLink"
  elementFormDefault="qualified"
  xmlns="http://www.w3.org/2001/XMLSchema" 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="
  http://www.w3.org/2001/XMLSchema http://www.w3.org/2001/XMLSchema.xsd
  http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd
  ">

  <import namespace="http://www.xbrl.org/2003/XLink" 
    schemaLocation="http://www.xbrl.org/2003/xl-2003-12-31.xsd"/>

  <import namespace="http://xbrl.org/2007/expression" 
    schemaLocation="expression.xsd"/>

  <element name="singleMeasure" substitutionGroup="xl:resource">
    <complexType mixed="true">
      <complexContent mixed="true">
        <extension base="xl:resourceType">
          <choice>
            <element name="qname" type="QName"/>
            <element name="qnameExpression" type="expression:expression"/>
          </choice>
          <anyAttribute namespace="http://www.w3.org/XML/1998/namespace" 
          processContents="lax"/>
        </extension>
      </complexContent>
    </complexType>
  </element>

  <element name="generalMeasures" substitutionGroup="xl:resource">
    <complexType mixed="true">
      <complexContent mixed="true">
        <extension base="xl:resourceType">
          <attribute name="test" type="expression:expression" use="required"/>        
          <anyAttribute namespace="http://www.w3.org/XML/1998/namespace" 
          processContents="lax"/>
        </extension>
      </complexContent>
    </complexType>
  </element>
</schema>	
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).
D	Acknowledgements (non-normative)
This document could not have been written without the contributions of many people including the participants in the XBRL Formula Working Group.
E	Document History (non-normative)
Date	Editor	Summary	
2006-12-18	Geoff Shuetrim	First internal working draft created, drawing extensively on the previous Formula specification drafts.	
2007-04-25	Geoff Shuetrim	Changed the target namespace of the normative schema.	
2007-05-08	Geoff Shuetrim	Added clarification about the fact aspect covered by the filters defined in this specification.	
2007-05-29	Geoff Shuetrim	Changed the target namespace of the normative schema again.  Modified the general unit filter to have a structure that is more consistent with the structure used for other filters.  Changed the $x notation to #x to be consistent with other filter specifications.	
2007-07-24	Hugh Wallis	Editorial for Publication	
F	Approval process (non-normative)
This section will be removed from the final recommendation.
This specification is being developed following the XBRL Technical Working Group Processes: http://www.xbrl.org/XSB/XBRL_Technical_Working_Group_Processes-Approved-2007-04-17.htm