XBRL (2)

Today offered a new opportunity to dive into XBRL. This time I concentrated on Taxonomies. What are taxonomies?

1. What is a taxonomy?
Basically, a taxonomy defines [u]what[/u/ should be in a report. The taxonomy is not the report itself, and it does not define the layout. It does define the elements that should be reported.

2. What about the layout of a report?
For the layout you can define a stylesheet.

3. What are the properties of elements in a taxonomy?
- data type:
- period
- balance
- nillable
That does not include any relations between elements, for that we have links.

4. What are the properties of links?
- references
- labels
- presentation
- versioning
- definition
The term presentation is slightly misleading, as it suggests it defines the way an element is shown. Actually it defines the place and sequence in which elements should be shown.

4. What is a linkbase?
A linkbase is simply a collection of links.

An element without links is called an unbound element.

Short descriptions:

• A reference link describes the relation between an element and the reporting standard such as IFRS
  
• A label link describes a link to a humanly readable description. For example, machines may not have trouble in using ifrs-ci_CashCashEquivalents, humans usually prefer something like Current Assets Label links may depend on the role of a link. One of the usages of role is to provide description in different languages. Another is to make a difference in description depending on value, for example loss for negative values and profit for positive values.
  
• A presentation link can not be used for layout, but can be used for defining relations between elements. Examples are Parent-child, or Order-Orderline. Another usage is to define the requirements that the presence of element A requires the presence of element B.
  
• The versioning link is used to define the changes in a taxonomy over time.
  
• The Calculation link describe show values of elements should be added or subtracted. It creates a relation between a summation element and a contributing element. It can be used as the base for the Formula linkbase.
  An example of a calculation link:
  <link:calculationLink xlink:type="simple" xlink:role="http://www.example.com/">
  <link:documentation>string
  </link:calculationLink>
  

5. What is a dimensional taxonomy?
A dimensional taxonomy allows the user to group data according to different dimensions. Examples are reporting by product (group), by geographic region, and by period.
Defining such taxonomies is not easy and may lead to high implementation costs.