Conventionally, the change log for taxonomies are documented in a free flow format, often supported by visual clues. The change log prepared for IFRS taxonomies is a good example for highlighting the changes. However, understanding the changes is not only for the taxonomy users, but also for the computer applications as well. To answer this need, XII has released the specification for ‘versioning”. It is commonly referred as Versioning Linkbase or Versioning Report. This document records the differences between two taxonomies in a standard and computer readable manner.
Let us look at some of the building blocks of Versioning Linkbase. The versioning linkbase is based on the XML syntax. This linkbase requires each and every changes to be classified according to its nature. As briefly mentioned above, changes can be on account of
● Change in reporting or disclosure needs (referred as business category)
● Change on account of including new specification (referred as technical category)
● Change to fix errors (referred as errata)
If we look at all the changes, then it might result in addition or deletion, change or renaming of taxonomy artefacts. The versioning specification consists of many modules, each having its own function. There are modules which can be used for describing changes in schema. For example, addition of new elements, deletion of existing elements or change in attributes for some elements. Similarly, there are modules designed for identifying the changes that are made in linkbases. Using these modules, it is possible to specify if any specific relationship or entire hierarchy of relationships has been added or deleted in the extended link role. Further, the changes in attributes of relationship like weight, order, use etc. can also be specified. In case of dimensional relationship, there is a provision to highlight the changes on primary concept, dimension and domain member combination.
The advantage of using versioning specification is not only to track the taxonomy changes logs in standard manner but also to facilitate and support presenting these changes to business users inthe least technical manner. The IFRS 2014 taxonomy is one of the recent examples where this versioning specification has been implemented.
This relatively new specification is trying to solve some problems in the world of XBRL and is slowly getting adopted. Though the specification has a wide coverage in terms of capturing the types of changes, there are some scope out areas as well, for the time being.
We encourage all the taxonomy authors and XBRL implementation community to follow this specification. In the event, if there any suggestions or additional scenarios to be taken care of in versioning specification, please get in touch with XII and also get involved in the working groups so that the additional needs and business requirements are considered and incorporated as well.