Defining Reporting Requirements

An XBRL taxonomy defines the reporting concepts that may be used in instance documents and can also provide a wide range of structured meta-data about the concepts and how they should be used.

Meta-data that can be defined using the core specifications (see XBRL Essentials) include:

Labels

Taxonomies can provide a variety of different labels. For example "standard labels" provide a general purpose label for a concept, whereas "documentation labels" can provide a more verbose description defining the purpose of the concept. All labels can be provided in multiple languages.

References

References provide structured meta-data, which can be used to provide links to authoritative reference material containing concept definitions.

Hierarchies

Concepts can be arranged into hierarchies that provide an organised presentation of concepts in the taxonomy (presentation relationships) or that capture certain arithmetic relationships between them (calculation relationships).

Dimensions

Taxonomies can use the specification to define hierarchies of dimensions that can be associated with concepts in order to report multi-dimensional data.

Meta-data is primarily contained in linkbases, which form part of the taxonomy:

Linkbase

A linkbase is an XML document that defines relationships using the W3C's XLink standard. Relationships are typically between concepts and other concepts, or between concepts and other resources such as labels.

A number of additional specifications have been developed in order to further enhance the ability of XBRL to define and manage reporting requirements.

Internationalisation and Translations

XBRL is an international standard and has been designed from the outset to support multiple languages and localised characters. All components in XBRL can be labelled in multiple languages, and the use of the linkbase mechanism makes it easy for third parties to define their own translations of taxonomies

Coping with change

A feature of just about every reporting domain is that reporting requirements evolve over time. In the XBRL world, taxonomies are often being continuously updated to reflect current requirements.

The Versioning specification enables taxonomy authors to provide structured information about the changes between different versions of an XBRL taxonomy. This can be used by preparers of XBRL reports in order to streamline the transition from one taxonomy version to the next, and by the consumers of those reports in order to enable comparison between different reports prepared against different taxonomy versions.

Units

All numeric facts in an XBRL report are associated with a unit declaration, describing the units in which a value is measured. The XBRL 2.1 specification requires that monetary facts are reported using standard units based on the ISO4217 currency standard, but does not prescribe units for the huge range of other types of values that may be reported.

The Units Registry 1.0 specification provides a central registry of units which are to be used with concepts of particular data types. This ensures that facts relating to the same type of value are reported with consistent units, simplifying comparison between different reports.

Tabular reporting

Reporting domains vary widely in the level to which the prescribe structure on their reports. For example, GAAP-based financial reporting typically allows considerable flexibility in the structure and presentation of reports, whereas prudential regulation requires reports that conform exactly to prescribed tabular structures, which are often highly dimensional in nature.

The Table Linkbase 1.0 specification makes it possible to define such reporting structures within XBRL taxonomies. This approach is discussed further under Presentation.

Business rules validation

Reporting requirements often translate into business rules to which all reports are expected to conform. XBRL makes it possible for many of these rules to be defined and published in a standard format. This is discussed further under Validation.