European XBRL Reporting Entities handbook
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CEN Workshop Agreement
Status: Working Group Working Draft
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Contents |
Foreword
This document is a working document.
This document has been prepared by CEN/WS XBRL, the secretariat of which is held by NEN.
This document is a working document.
Introduction
Scope
The objective of this CWA is to provide a roll-out package for regulators who wish to use XBRL. More precisely, this CWA consists of two parts:
- i) An XBRL supervisory roll-out guide: this is oriented towards national regulators on how to implement, extend and manage XBRL taxonomies
- ii) An XBRL handbook for declarers: this is a roll-out guide or reference handbook would give a general introduction to XBRL and serve as a help to preparers of XBRL (reporting entities)
The scope of the current document is on the second part of the CWA; the XBRL handbook for declarers. In this general guide to XBRL, the following subjects will be addressed: [DRAFT]
Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
EN xyz:199x, Title of the european standard.
EN ab c:199x, General title of series of parts — Part c: Title of part.
Terms and definitions
For the purposes of this document, the following terms and definitions apply / the terms and definitions given in … and the following apply.
- Term1
- description on text for term1
- Term2
- description on text for term2
XBRL Introduction
Introduction: from unstructured to structured information
Before starting to explain XBRL, we would like to show via an example why the structuring of reported data can be useful. Reported financial data tend to be represented a table format. For example, the COREP Capital Adequacy table looks this:
[Image: Example COREP Reporting table]
Such a representation of information is very human-readable. However, it is not ideal for machine interpretation, as it is not very structured. As a result, the following question comes to mind: How can we structure this information, so that it can be transmitted and interpreted in a consistent way? For the purpose of this example, we’ll focus on the “Eligible Capital” line, which is highlighted in yellow in the above example.
A first step would be to tag the amount of Eligible Capital in a way that it is directly linked to the concept of Eligible Capital:
[Image: Code tag Sample1]
Although this information is already quite structured, some contextual information is missing. Information like the currency of the amount:
[Image: Code tag Sample2]
And finally, the reporting period:
[Image: Code tag Sample3]
The above example shows, in a nutshell, how XBRL allows to structure reporting data.
General Definition of XBRL
XBRL, or eXtensible Business Reporting Language, is a communication standard developed in order to simplify the exchange of business and financial data.
XBRL normalises the format of data (via the use of XML techniques) en the validation of data (via XBRL taxonomies).
[Image: XBRL Language Dagram]
XBRL also provides among others:
- Standard validation rules (mathematical and logical rules)
- The use of label linkbases (which allows multi-lingual taxonomies)
- The possibility to provide rendering
- Standard toolset which allow to work with XBRL
XBRL Components
XML
XML, or eXtensible Markup Language, is a W3C standard which allows to represent structured data in the form of flat text. This representation is both machine readable as human readable.
Simple XML example:
[Image: Code XML Sample 1]
XML languages use elements & attributes in order to structure content. The XML specification defines the syntax of elements, attributes en other structures which can appear in XML documents.
XML Schema (XSD) is a language used for describing the structure of XML documents. XML Schema allows the creation of schema's of for example XML-documents, by which these documents are formally specified and by which they can be validated by XML validators. An XML Schema provides among others what the elements of an XML document are, where they appear, what characteristics must be respected, etc…
An XML document can be correct (well-formed) according to the general XML standard, but also invalid according towards a specific XML Schema.
[Further explain XML and components like: XML namespaces, XML schema, XPath, XLink, XPointer]
XBRL Taxonomy
[Chapter explains the main purpose of XBRL taxonomy (definition of reporting concepts)]
An XBRL Taxonomy is a collection of taxonomy schemas and linkbases. A taxonomy schema is an XML schema document (file). Linkbases are XML documents (file) which follow the XLink specification. The schema must ultimately extend the XBRL instance schema document and typically extend other published XBRL schemas on the xbrl.org website.
Taxonomy schemas define Item and Tuple "concepts" using <xsd:element> elements. Concepts provide names for the fact and indicate whether or not it's a tuple or an item, the data type (such as monetary, numeric, fractional, or textual), and potentially more metadata. Items and Tuples can be regarded as "implementations" of concepts, or specific instances of a concept. A good analogy for those familiar with object oriented programming would be that Concepts are the classes and Items and Tuples are Object instances of those classes. This is the source of the use of the "XBRL instance" terminology. In addition to defining concepts, taxonomy schemas reference linkbase documents. Tuples instances are 1..n relationships with their parents; their metadata is simply the collection of their attributes.
Linkbases are a collection of Links, which themselves are a collection of locators, arcs, and potentially resources. Locators are elements that essentially reference a concept and provide an arbitrary label for it. In turn, arcs are elements indicating that a concept links to another concept by referencing the labels defined by the locators. Some arcs link concepts to other concepts. Other arcs link concepts to resources, the most common of which are human-readable labels for the concepts. The XBRL 2.1 specification defines five different kinds of linkbases:
- Label Linkbase
- Reference Linkbase
- Calculation Linkbase
- Definition Linkbase
- Presentation Linkbase
[TODO: add more details on the linkbases
XBRL Instance Document
The XBRL instance begins with the <xbrl> root element. There may be more than one XBRL instance embedded in a larger XML document. The XBRL instance itself holds the following information:
- Business Facts: facts can be divided into two categories
- Items are facts holding a single value. They are represented by a single XML element with the value as its content.
- Tuples are facts holding multiple values. They are represented by a single XML element containing nested Items or Tuples.
In the design of XBRL, all Item facts must be assigned a context.
- Contexts define the entity (e.g. company or individual) to which the fact applies, the period of time the fact is relevant, and an optional scenario. Date and time information appearing in the period element must conform to ISO 8601. Scenarios provide further contextual information about the facts, such as whether the business values reported are actual, projected, or budgeted.
- Units define the units used by numeric or fractional facts within the document, such as USD, shares. XBRL allows more complex units to be defined if necessary. Facts of a monetary nature must use a unit from the ISO 4217 namespace.
- Footnotes use XLink to associate one or more facts with some content.
- References to XBRL taxonomies, typically through schema references. It is also possible to link directly to a linkbase.
SHOW (via a practical example) how an instance document is constructed: namespaces, contexts & units, facts, …
Practical example: from financial report to XBRL instance
Show a (real?) use case which is relevant for the declarer of XBRL: how to go from report & taxonomy to XBRL instance
Bibliography
- [1] :xxx
- [2] :xxx
