European XBRL Taxonomy Architecture V2.0
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CEN WS XBRL Experts: Thierry Declerck (DFKI), Roland Hommes (Rhocon), Katrin Heinze (Deutsche Bundesbank)
Contents |
Foreword
Introduction
The purpose of this document is to present and explain the European XBRL Taxonomy Architecture (EXTA) defined by European supervisory authorities. In particular, it explains the scope (coverage of information requirements), modularization in files, manner of defining concepts and relations and other important design aspects. It is fully compatible with the Data Point Methodology approach. As DPMs are semantic models being created by supervisory experts, they are not formalized from a technical point of view. XBRL as formal language can fill this gap. XBRL as data format is standardized and can therefore be used to enable automated processes. XBRL taxonomies are metadata specifications that provide a formal description of the data requirements to be used as data format in the European reporting process.
These pages are hosting the guidelines to an European XBRL Taxonomy Architecture (EXTA).
- European: this project is funded by the EU commission to support the standardisation process for supervisory reporting in Europe, but there is no restriction in applying it anywhere else;
- XBRL: this format has been chosen by the supervisory authorities EBA and EIOPA for the electronic data exchange between national banking supervisors and the European authorities;
- Taxonomy Architecture: this architecture has been created to limit the wide variety of options to define an XBRL taxonomy; different European XBRL taxonomies for similar purposes cause incompatability and would lead to increased implementation costs for all adopters in the EU market.
Objective
The objective of the EXTA is to define a set of architecture guidelines that transforms an European DPM without a loss in quality in an XBRL format. The taxonomy architecture provides a set of rules for this transformation to enable the creation of consistent and predictable XBRL meta data definitions in an automated process. EXTA supports a modular structure to enable the extensibility of these taxonomies as well as to ease their maintenance. As EXTA is a formal representation of a DPM it contains several structural concepts which has no correspondance in other known XBRL architectures.
Target audience
EXTA is targetted at taxonomy authors. Initially organisations like EBA, EIOPA, ESMA, ECB etc. As a spin-off of these taxonomies, local (national) initiatives will emerge, hosted by National Supervisory Agencies (NSA's). To meet local legislation the European taxonomies may need to be extended with local requirements. The EXTA is also aimed at supporting these national extensions according to the same guiding principles. The main advantage being a consistent framework of XBRL taxonomies which enables a cost efficient implementation in software solutions.
Consistent taxonomies throughout Europe also creates the opportunity for cross-EU harmonisation of terminology and, in a later stage, consistent reported facts that are more easily analyzed since the underlying structure is the same and terms used are complementary to each other.
A consequence of a consistent taxonomy framework is that software developers can choose to support only the architectural guidelines of EXTA. Although this limits their software in supporting full fledged XBRL taxonomies it eases implementation costs.
This document is aimed at users of the Bundesbank taxonomies, in particular editors of the taxonomy or producers of instance documents (by applying mappings to internal systems or assigning XBRL tags with values in any other manner) as well as developers of the IT solutions facilitating reporting in the XBRL format or analysis of XBRL data.
Relationship to other work
The reader of this EXTA is expected to be familiar with the principles of data modelling and have a thorough understanding of the XBRL family of specifications to evaluate the impact of the rules set to the XBRL taxonomy that needs to be created.
Scope
The EXTA has been defined for the creation of XBRL Taxonomies in the context of European supervisory reporting. XBRL taxonomie following this architecture are published by an European supervisory authority to reflect the data requirements based on a DPM in a machine-readable form.
Normative references
The eXtensible Business Reporting Language (XBRL), see | XBRL Standard
The Extensible Markup Language (XML), see | XML Standard
Terms and definitions
- Concept
- A concept is an XML element defined in the substitutionGroup xbrli:item or xbrli:tuple.
- Data Point Model (DPM)
- A DataPointModel defines structures of data describing the characteristics of the information exchanged in the context of supervisory reporting processes.
- Dimension
- A Dimension is a data set to one characteristic area which is composed of individual and non-overlapping data elements. In XBRL terms a dimension is an abstract concept in the substitutionGroup xbrldt:dimensionItem.
- Domain
- A Domain is a classification system to categorize items that share a common semantic identity. A domain is an abstract concept and is the parent in a domain-member relationship. E.g. all individual countries can be members in a domain 'Countries'.
- Family
- Families are groups of Dimensions relevant for presentation or querying purposes. In XBRL terms a family is an abstract concept in the substitutionGroup xbrli:item with the @type set to 'model:familyType'.
- Framework
- A Framework is a business term common to a group of business users that consists of reporting regulations for a domain specific scope of information, like COREP, FINREP or Solvency II. Frameworks are public elements represented using XBRL abstract items with @type set to 'model:frameworkType' in schema 'fws.xsd'.
- Item
- An item is an abstract XML element in the substitutionGroup xbrli:item that can be used to carry facts or to represent business measurements. The item is defined by XBRL International as a placeholder for creating concepts.
- (Domain) Member
- A domain-member is discrete and countable. These Members can be explicitly defined in a domain. A member is an abstract concept in the substitutionGroup xbrli:item and is the child in a domain-member relationship.
- Metric
- A metric represent the nature of the data with a fixed and unchangeable meaning. Metrics are strongly related to the underlying data type. Mostly they are numeric and quantitatively measurable but they can be also reflect boolean or date values. A metric also known in XBRL terms as primary is a non abstract concept in the substitutionGroup xbrli:item that is defined based on the unique combination of a (XML) type and xbrli:periodType.
- Namespace
- The unique string in the form of an URI that is the @targetNamespace content of (a set of) XML schema file(s).
- Owner
- The owner represents an European institution that defines concepts. The owner's namespace is a URI used to establish the namespace of the concepts defined by that owner.
- Perspective
- Perspectives are extended linkroles that have a child node <link:usedOn>link:presentationLink</link:usedOn> AND contain only parent-child relationships in which families are the parent and dimensions are the child.
- Public elements
- Public elements of DPMs are represented as concepts in XBRL taxonomies. They are identified by a code in a certain scope. They MAY include additional information such as readable labels, definitions and legal references in different languages.
- SubstitutionGroup
- An XML attribute to classify a complexType of simpleType element so its construction can be re-used by other elements.
- TableGroup
- A TableGroup is a set of Tables that represents a business template. In XBRL terms tableGroups are public elements represented using XBRL abstract items with @type set to 'model:tableGroupType'.
- Taxonomy
- Taxonomies are defined as part of the DPM. It represents a version of the framework; kind like a 'name' for the set of definitions used in the framework that are not part of the dictionary. There is a virtual link with the XBRL term 'taxonomy' which is a set of concepts with their relationships and definitions. The XBRL taxonomy has much wider definition than the EXTA one. Taxonomies are public elements represented using XBRL abstract items with @type set to 'model:taxonomyType' in schema 'tax.xsd'.
European XBRL Taxonomy Architecture
Public elements
Public elements are all concepts based on a DPM that are identified by a code in a certain scope and may include some additional information such as readable labels, definitions and legal references in different languages.
Public elements include two attributes to reflect their creation date (model:creationDate) and the date when they was last modified (model:modificationDate).
Language specific information of public elements is represented using the following label resources: XBRL 2.1 labels (link:label) for xbrli:items (or derived) public elements,
- generic labels (label:label) for public elements represented as XLink resources or other construct (e.g. link:roleTypes).
- The default (standard) role (http://www.xbrl.org/2003/role/link) is used for the extended links containing the label resources.
The role types used as roles for generic and standard label resources are presented in the following table.
| Property | Generic label role | Standard label role |
|---|---|---|
| Name | http://www.xbrl.org/2008/role/label | http://www.xbrl.org/2003/role/label |
| Definition | http://www.xbrl.org/2008/role/verboseLabel | http://www.xbrl.org/2003/role/verboseLabel |
| Legal references | http://www.xbrl.org/2008/role/documentation | http://www.xbrl.org/2003/role/documentation |
The labels of the concepts of a schema or a linkbase file are represented jointly in a separate label linkbase file distinguished by language, in the same folder as its corresponding schema or linkbase file. Each language is stored in a separate label linkbase file. The naming convention for these label linkbase files is:
- {main-file}-lab-{lang}.xml
where {main-file} corresponds to the name of the schema or linkbase file where the concept is defined (without extension) and {lang} component represents the ISO 639-1 code of the language (lowercase).
In addition to this, some concepts of the dictionary may contain a special linkbase to represent codes needed for different purposes. In particular, the codes given to the columns and rows of tables or codes assigned to the data points are represented using this mechanism. The name of these linkbase files constructed as follows:
- {main-file}-lab-{lang}-codes.xml or {main-file}-lab-codes.xml
In case of the later, the distinction between codes appearing in different language versions is determined basing on xml:lang attribute on label resources. The labels for these codes are represented as resources with a custom role. The role defined in the model.xsd schema for resources representing codes of rows or columns is http://www.eurofiling.info/xbrl/role/rc-code.
Taxonomy levels and owners
Taxonomy concepts could be defined on one of the three levels:
- cross sector concepts and breakdowns (to be shared between different institutions e.g. banking, insurance and securities supervision),
- concepts from information requirements of an European supervisory authority,
- concepts defined by a NSA.
Level one are cross sector concepts that shall be eventually defined and agreed by a joint group of experts involved in setting up information requirements for different sectors such as banking, insurance and reporting of other commercial and non-profit companies. It is expected, that these concepts will mainly include the list of countries and currencies as defined by the ISO codes and subsequently extended by for example economy sectors, classes of financial instruments, accounting portfolios, time intervals, etc. This task will be most likely conducted by reconciliation between the dictionaries of business concepts defined by the EBA, EIOPA and other interested parties. Cross sector concepts will be published in the Eurofiling on-line resources as a set of XBRL schema and linkbase files that can be referenced from level two or level three dictionaries.
Level two are the concepts of an European supervisory authoriy. They represent the information requirements of COREP, FINREP, Solvency II and other scope defined on the European level. They may refer to and extend level one (cross-sector) concepts.
Level three are the concepts of national supervisors. They reflect information requirements set by a national legislation and specific banking regulations.
The idea of levels for concepts definitions has been addressed in the XBRL taxonomy model by introducing the notion of the owner. The owner represents an institution that defines concepts of the model. The owner is closely related to the idea of extensibility in XBRL. The main properties of the owner are:
- owner’s namespace {ons},
- owner’s prefix {opre}, and
- official location {oloc}.
The owner namespace {ons} is a URI used to establish the namespace of the concepts defined by that owner. This URI is generally built by adding xbrl to the internet domain of the institution that the owner represents. In case of the Bundesbank, the domain is extended by stat and sprv components to distinguish between statistical and supervisory datasets. The prefix {opre} is used as the basis to establish namespace prefixes in taxonomy files and for some short representations of the concepts by QNames using shorter prefixes (instead of long namespaces) plus the local name.
Official location {oloc} is a URL used to specify the location where taxonomy files associated to that owner are to be published. Different owners must have different official locations, even owners with the same internet domain/same namespace. The official location is generally built by adding three parts to the internet domain of the institution:
- representation of the geographical area covered by the institution (e.g. eu in case of the cross sector or the EBA concepts or de for the Bundesbank specific concepts applied in Germany),
- indication of the scope of information requirement (e.g. fr for general financial reporting, stat for statistical data, sprv for supervisory data, etc)
- fixed xbrl component identifying the type of standard used to express information requirements.
The following table presents examples of owners and applied namespaces, prefixes and official locations of taxonomy files.
| Owner | Namespace | Prefix | Official location |
|---|---|---|---|
| Cross-sector | http://www.eurofiling.info/xbrl | eu | http://www.eurofiling.info/eu/fr/xbrl |
| EBA | http://www.eba.europa.eu/xbrl | eba | http://www.eba.europa.eu/eu/fr/xbrl |
| Banca d’Esmirna | http://www.bde.se/xbrl | se | http://www.bde.se/se/fr/xbrl |
