XBRL Definition Linkbase

From Open Risk Manual

Definition

The XBRL Definition Linkbase associates concepts with other concepts using a variety of arc roles to express relations such as is-a, whole-part, etc.

Usage

Arc roles can be created by those who create XBRL taxonomies or commonly used arc roles can be added to the XBRL Link Role Registry (LRR).

The definition linkbase provides taxonomy creators with the opportunity to define different kinds of relations between elements. There are four standard types of relationships supported by the definition linkbase:

  • general-special. It distinguishes between concepts that have more generic or more specific meaning. For example, ZIP code is the US representation of Postal Code which is used worldwide. Therefore, to indicate that connection, taxonomy creators define Postal Code as a general term to which there is more specialised concept ZIP code.
  • essence-alias. By using it, taxonomy creators are able to indicate that two concepts have similar meaning. For example, some airlines may want to use the term Planes to describe their main component of their Property Plant and Equipment (PPE) while other would prefer Aircraft. To state that the meaning of these two is the same and that they can be used interchangeably, taxonomy creators may connect them using "essence-alias" arcrole.
  • requires-element. As its name indicates, taxonomy builders use it to force instance creators to enter the value of one element, if they provide the content of another. For instance, a regulator may want to require disclosures on a particular component of Assets if it appears on the Balance Sheet. In order to achieve that, the definition linkbase defines "requires-element" relationship between them (for example, Property, Plant and Equipment, Net and Property, Plant and Equipment Disclosures).
  • similar-tuples. It resembles "essence-alias" relation but is applied for tuples. It connects two tuples that are equivalents in terms of definition (documentation from label linkbase or reference in reference linkbase) but are diverse from XML perspective i.e., do not have identical content models, for example contain different elements. One of the reasons that this type of relation was introduced is the prohibition of schema redefinition which prevents changes in a tuple's content model.