Table of Contents

1 Abstract

This guidance provides an introduction to the topic of taxonomy labels, and provides guidance on approaches for standard labels creations for taxonomy elements. This guidance is targeted towards taxonomy architects and taxonomy authors.

2 Taxonomy labelling

Labels are essential to make a taxonomy that can be read and understood by people, rather than only computers. Labels can be provided for a wide variety of taxonomy components, including taxonomy elements, extended link roles, custom data types, XBRL formula rules, and rows and columns in an Unresolved reference 'xg:XBRL reporting template'.

A single taxonomy component can have more than one label. Labels can be provided in multiple languages and can be of different types.

Provision of labels in multiple languages allows the taxonomy, and XBRL reports that use it, to be understood in different languages. A separate guidance document discusses the creation of multilingual labels.

Different label types are identified using "label roles", which defines the purpose of the label. The XBRL specification defines a "standard role" which is used to provides a default label known as the "Standard Label". This guidance focuses on standard labels for taxonomy elements. A separate guidance document provides recommendations on other label roles.

Creating good labels is a key part of creating a good taxonomy, and taxonomy authors must consider how labels are created and used to the best effect.

3 How to create good standard labels

A concept's standard label will be used by default to provide a name for the concept, and so it is important that every concept has a standard label that accurately describes the concept. In order to ensure that concepts have clear and consistent standard labels throughout a taxonomy, it is recommended that a taxonomy architects define a convention for the construction of taxonomy labels.

This guidance explains properties of a good standard label and presents a number of different possible labelling conventions.

4 What makes a good standard label

Good standard labels will have the following properties:

Standalone and unique

Standard labels should be sufficient to identify a concept without reference to its position within a hierarchy such as the presentation tree. Standard labels should also be unique within the taxonomy. For example, a concept such as "Other deductible expenses" should not have a standard label of "Other" as this on its own is not sufficient to convey the meaning of the concept, and is unlikely to be unique ("Other" may be appropriate as a terse label).

Useful

Labels should describe a concept in such a way that it accurately describes the meaning of the concept. Avoiding acronyms not familiar to the users of the taxonomy can be applied as one of the rules to create useful standard labels. For concepts that can take both positive and negative values, standard labels should describe the meaning of a negative number in parentheses. For example, a negative value reported for a concept with the standard label "Other Income (expense)" would indicate that value represents an expense. Handling positive and negative values in XBRL is described in more detail in a separate guidance document

Role independent

Standard labels should not reflect a particular usage of a concept. For example, XBRL best practice requires that the same concept is used to represent both opening and closing balances; these are the same concept, but reported at different points in time. As such, "Opening Balance, Cash and cash equivalents" should not be used as a standard label. Instead, the standard label should be "Cash and cash equivalents", and separate labels should be used to reflect opening and closing balances. The use of label roles to differentiate different types of label is discussed in more detail in a separate guidance document.

Concise

Labels should be as concise as possible whilst still meeting the other criteria for good standard labels.

Consistent

Labels should be defined using a consistent construction pattern, allowing users to understand the label better across concepts in the taxonomy. For example, if the term "Non-current" needs to be included in labels it should be consistently used either as a suffix or prefix throughout the taxonomy.

5 Standard label creation approaches

This section describes different approaches that can be used to create standard labels. The approaches presented are:

• Reuse existing non-XBRL labelling
• Use a formal structure
• Creating labels using business knowledge

5.1 Reuse existing non-XBRL labelling

Many XBRL programmes are replacing or extending existing reporting mechanisms. For example, there may be an accounting standard or an existing form that provides the basis for the creation of the concept. The descriptions of what should be reported has already been thought through and decided upon either in forms, accounting or regulatory standards. Often these descriptions are part of the common vocabulary of organisations that are reporting.

This labelling approach is characterised by taking the existing non-XBRL definitions and simply copying them into the appropriate XBRL labels. This leads to labels that are accurate, and may be familiar, but may not fulfil all the properties of a good standard label.

An example of 'Non-XBRL Labelling' for the concept 'Policy for Measuring Inventories' would be to adopt the exact term 'The accounting policies adopted in measuring inventories, including the cost formula' as defined in the accounting standard.

Characteristics and consequences:

• Reusing existing labels should mean that minimal effort is required for labelling.
• As the labels are a copy of the framework it is capturing, there is a clear link between the taxonomy and the existing framework that may help in understanding the taxonomy.
• Lack of control over the label construction may lead to issues in clarity, consistency or conciseness of the label
• In some cases, the copying of labels from non-XBRL sources may mean that the text loses its meaning (e.g., references to pages, columns, rows or other aspects of the source material that is not carried into the XBRL)
• References provide a better mechanism for defining structured links to authoritative definitions.

5.2 Creating new labels using a formal structure

To ensure that labels are unique and standalone, this approach starts with a formal structure of concept definitions and builds the label from parts of the hierarchy in this structure. Labels created in this way reflect the hierarchy and drill-down approach related to either the structure of the taxonomy.

An example of following a hierarchy defined in a business template is given below:

• Assets
  • Goodwill
  • Biological
  • Other

Labels following a formal structure derived from the above hierarchy could be:

• Assets
  • Assets, Goodwill
  • Assets, Biological
  • Assets, Other than goodwill and biological assets

Characteristics and consequences:

• This approach delivers unique labels without having to consider the complete set of labels.
• Labels are applied consistently across the whole taxonomy.
• Parts of the label creation process can be automated.
• Labels must be maintained in line with the taxonomy structure (which can mean an increase in taxonomy maintenance cost).
• This approach typically leads to longer labels failing to meet the requirement for conciseness).
• This approach effectively prevents the reuse of concepts within the presentation tree as the standard label would not be able to represent both locations (preferred labels would have to be used in order to re-use concepts within the presentation tree).

5.3 Creating labels using business knowledge

Under this approach, business knowledge is used in order to define labels that are unique across the taxonomy without being unnecessarily verbose.

To ensure consistency in the structure and wording of labels, while maintaining readability, this approach starts from a natural description of the concept and applies a set of steps in order to make it appropriate for the taxonomy.

Steps may include applying a combination of rules and judgement to ensure that labels are concise, whilst still ensuring that the labels are useful, standalone, role independent and consistent.

For example; 'investments accounted for using the equity method' might be converted to 'investments, equity method' by identifying key terms and removing words that can be reasonably inferred. These steps would be applied consistently to other labels. Characteristics and consequences:

• Labels are consistent across the taxonomy.
• Information that is implicitly or explicitly included in a concept by the use of XBRL is not repeated in the label (e.g., if the concept is of type monetary, then there is no need for the label to restate that the concept represents a monetary amount).
• Leads to concise labels through the explicit removal of implied words such as 'Total' and 'Amount of'.
• This is a labour-intensive way to create a label.
• The guidelines essentially create a taxonomy grammar (may not follow normal grammar) that would need to be understood by the users of the taxonomy so that they can read the labels properly (e.g., 'Risk, after mitigation' and 'Profit, gross').
• Separate label construction guidelines for each language may be required.

5.4 Guidance - Standard label creation approaches

Based on the above analysis, the recommended approach to creating standard labels is to create labels using business knowledge.

In order to create labels consistently, it is necessary to define the conventions to be followed for label construction. This will include details such as capitalisation of words, use of acronyms, and which connecting words should be included or omitted.

It should be noted that the architectural choice of label construction is one that is particularly difficult to change once the taxonomy is in production, due to the reliance on them by users, so the adopted conventions should be considered and tested carefully.

The conventions adopted should be clearly documented so that any future additions to the taxonomy can be done consistently.

6 Examples of standard label construction

Table 2 gives examples of labels that would not meet the criteria for good standard labels described in Section 4 and provides suggested replacements.

7 Technical note on label construction

In a taxonomy, labels can be assigned to taxonomy elements using a technical construct referred to as the "Label Linkbase". Another mechanism, known as "Generic Labels" can be used to label all taxonomy components, including data types and extended link roles as well as taxonomy elements.

It is recommended to use the "Label Linkbase" mechanism for taxonomy elements and "Generic Labels" for other taxonomy components. This guidance is in accordance with the standard approach followed in most taxonomies and the implementation styles supported by the majority of software applications.