Table of Contents

1 Introduction

XBRL taxonomies provide a standard way of defining the content of reports, including multi-lingual labels, references to authoritative documentation, and automated business validation rules. In order to facilitate adoption and correct reporting by users of the taxonomy it is recommended that each taxonomy is published with supporting documentation. This guidance recommends the basic documentation that should be published alongside the taxonomy. This guidance is intended primarily for taxonomy owners and data collectors.

2 Taxonomy Supporting Documentations

This section lists essential supporting documentation for taxonomy publication.

2.1 Taxonomy Package

Taxonomy owners should publish the taxonomy as a Taxonomy Package. A Taxonomy Package is a specially formatted ZIP file that provides additional information about the taxonomy. It is recommended that the taxonomy package contains sufficient information to make the broad purpose and scope of the taxonomy clear to a user who is unfamiliar with the filing system. See here for further guidance on the contents of Taxonomy Packages.

2.2 Taxonomy Architecture

Taxonomy owners should publish their taxonomy architecture to explain the logical and physical modelling of the taxonomy and how it maps to the underlying reporting requirement. It should explain the usage of custom components, the taxonomy’s style guide, versioning and deprecation mechanisms. These help the users better understand the taxonomy and how it should be used.

2.3 Preparers’ Guide

It may be necessary to publish a preparers' guide explaining how to use the taxonomy in the particular reporting environment. The guide is provided for preparers and software developers who need to use the taxonomy to create valid XBRL reports. The guide should explain the principles to be applied when creating XBRL reports for the specific reporting environment. The Preparers’ Guide may cover topics such as completeness of tagging, use of extensions (when allowed), the precision to which facts need to be reported, and other requirements defined by the collector. The preparers’ guide generally covers two main topics, filing guidance and filing rules as explained below:

2.3.1 Filing guidance

Filing guidance covers non-automatable rules and tagging guidance to help preparers create XBRL reports. These may include:

• Applicability of the taxonomy. In other terms, who should file, when and what parts (if not all) of the taxonomy should be reported.
• Guidance on how to choose the right tags from the taxonomy or when it is necessary or acceptable to add new elements.
• Instructions for preparers on how to create and name the report files.
• Workflow for validation and submission of XBRL reports.
• In cases where the taxonomy is extensible by preparers, the preparers' guide should include guidance for extensions.

The application of such guidance cannot typically be automatically validated by XBRL processors, as it requires the judgement of preparers to apply correctly.

2.3.2 Filing rules

Filing rules are validation rules that are driven by the technical requirements of the reporting programme in order to ensure interoperability. Examples of filing rules include specifying which versions and modules of the XBRL specifications may be used in filings, any applicable file size limits, and restrictions on if and how extension taxonomies should be constructed. Data collectors should publish filing rules if they require preparers to comply with these technical requirements. A separate piece of guidance discusses the broad principles for creation and publication of filing rules and there are checklists for XBRL report and taxonomy extension filing rules.

2.4 Changes between versions

Where a published taxonomy is a new version of an existing taxonomy, it is useful for taxonomy publishers to communicate the differences and similarities between the taxonomy versions. The contents of such a report will depend on the audience. For example, for software vendors changes in taxonomy architecture would be of interest, whereas preparers would be interested in new or deprecated concepts which will impact their report. The XBRL Versioning Report provides a standardised, structured format for communicating the differences between taxonomy versions.

2.5 Sample reports

Sample XBRL or iXBRL reports should be included as part of the taxonomy documentation where possible. These are useful for testing and to gain a better understanding of the taxonomy. The most useful sample reports are illustrative examples containing realistic sample data and should reflect the type and range of data for which the taxonomy will typically be used. The samples should be provided as XBRL or iXBRL, as applicable, and should be valid according to all applicable validation and filing rules. Where XBRL Reporting Templates are used, users of the taxonomy may find it useful to be provided with empty spreadsheet templates in addition to sample reports.

3 Sample References

Below are some examples of taxonomy documentation for taxonomies with wide user bases.

• LEI Taxonomy Package
• U.S. GAAP Financial Reporting Taxonomy Implementation Guides
• Using the IFRS Taxonomy—A preparer's guide
• EBA taxonomy and supporting documents (v2.9)
• EIOPA Supervisory reporting Taxonomy and supporting documents
• IFRS Taxonomy illustrative examples – sample instance document
• XBRL FRC UK Taxonomies and supporting materials
• Dutch SBR Taxonomies and supporting materials