XBRL Core Taxonomy Information Requirements 1.0

Requirements Document 20 January 2022

This version
Mark Goodhand, CoreFiling <mrg@corefiling.com>
Paul Warren, XBRL International Inc. <pdw@xbrl.org>

Table of Contents

1 Core Taxonomy Information Requirements

1.1 Overview

The XBRL v2.1 specification, and most subsequent modules are defined in terms of the XML syntax of component documents, and do not explicitly define the semantic information that may be represented in and inferred from XBRL documents.

With the development of the Open Information Model 1.0 ("the OIM Report Model"), this has largely been addressed for the information represented by an XBRL Report.

It is proposed that a corresponding OIM Taxonomy Model be developed, to provide a syntax-independent definition of the information in an XBRL Taxonomy. Due to the breadth and variety of information defined in an XBRL Taxonomy, it is intended to tackle this in phases.

This document captures requirements for the first phase of an OIM Taxonomy Model. This is the first part of a phased approach, which is described in the OIM Taxonomy Model Implementation Plan Working Group Note.

This phase, referred to as Core Taxonomy Information (CTI), is intended to capture the taxonomy information needed by a processor implementing the OIM Report Model (see Section 1.5.2).

1.2 Goals

The primary goal of the Open Information Model Working Group is to ensure that XBRL remains relevant in the face of changing technologies by defining XBRL semantics in a syntax-independent manner. Specifically, this means:

1.3 Initial Deliverables

The initial deliverables of the Core Taxonomy Information effort should be:

1.3.1 Round-tripping

It should be possible to convert a model-based representation of a taxonomy to the XML-based syntax and back again, resulting in an equivalent taxonomy model (sec Section 1.5.4). Note that the Core Taxonomy Information is only a subset of the information in an XBRL Taxonomy (see Section 1.5.2), and so round-tripping from XML to CTI model and back is a potentially lossy transformation.

1.4 Use Cases

Possible use cases for the deliverables are documented below.

1.4.1 Creation of an XBRL API

A software developer may wish to develop an XBRL API that exposes a logical interface onto the data in an XBRL taxonomy. The CTI should enable as much syntactic detail as possible to be omitted from the API, and should make it possible to define an API that can be backed by alternative representations of XBRL (e.g. a database) without loss of functionality.

1.4.2 Supporting simple analysis of xBRL-JSON data

A consumer may wish to analyse XBRL data that has been published in xBRL-JSON format. Whilst the xBRL-JSON format is relatively simple, in certain cases correctly interpreting the data requires some taxonomy information. For example, it is necessary to know where fact and dimensions have QName values. In addition, as xBRL-JSON uses JSON strings for all fact and dimension values, correctly identifying numeric values requires some datatype information from the taxonomy.

1.4.3 Supporting shredding of XBRL data to a database

A consumer of XBRL reports may wish to store reports in a database. The CTI should provide all the information required to losslessly store an OIM-compatible XBRL report in this way.

This use case shares many of the same requirements described in the preceding use case.

1.4.4 Report augmentation

A software developer may wish to create a standalone document that combines all information from an OIM-compatible XBRL Report with the taxonomy information needed in order to correctly interpret the report data. This could be done by adding information at the permitted extensibility points of the xBRL-JSON format. The CTI should provide the information necessary for this conversion.

1.4.5 Creation of simple taxonomies

A user wishing to use XBRL for internal data processing needs may wish to create a minimal XBRL taxonomy in order to support this. For example, a user wishing to import CSV files into an OIM-compatible database may wish to define a taxonomy that contains the information necessary to perform this transformation without creating an XBRL taxonomy in XML syntax.

1.5 Requirements

1.5.1 Audience

The CTI Model will unavoidably need to deal with technical detail as the starting point is the existing XBRL specifications which define XBRL in terms of a syntax rather than a logical model. As such, the model will need to reference the technical terms used in those documents, but, insofar as possible the constructs defined by the CTI Model should use terminology that will be meaningful to business users.

1.5.2 Scope

The CTI Model is intended to be the first step in a phase approach to modelling XBRL taxonomy information. The scope for the CTI deliverable is to model all taxonomy information that is required by a conformant processor implementing the Open Information Model, xBRL-CSV or xBRL-JSON specifications.

This means that features that are not required by such a processor, such as labels, references and inter-concept relationships, are out of scope for this phase.

Note that scope for the CTI Model is limited to conformant processors, as opposed to validating conformant processors. Any information that is only required by the latter is considered out of scope for the CTI Model. Most notably this means that full XML Schema datatype information, and most dimensional taxonomy information are not required.

1.5.3 Completeness

The CTI Model must represent the implicit and explicit semantics currently captured in XBRL constructs that are in common use, and which are considered consistent with current XBRL best practice. It is not necessary for the Model to represent everything that is currently possible within XBRL’s XML syntax. It is acceptable for the CTI Model to omit certain XBRL features in order to achieve a clean, and portable model.

Note that the completeness requirements are independent of the scope requirements discussed above. Features that are omitted purely because they are out of scope for CTI will be included in future phases. Features that are omitted because they are deemed undesirable under this requirement will not be added in the future.

1.5.4 Semantic equivalence

The CTI model should make it possible to determine if two taxonomies, possibly in two different syntaxes, communicate the same essential taxonomy information. Such comparison is limited to the scope of the CTI Model (see Section 1.5.2).

1.5.5 Specifications covered

The CTI Model must capture semantics represented in XBRL taxonomies conforming to the following XBRL specifications, although as noted in Section 1.5.3, the model may exclude certain features from these specifications:

1.5.6 Omission of XML-specific data structures

The CTI Model should, wherever possible, avoid modelling information that is inherently tied to XML syntax.

Appendix A Intellectual property status (non-normative)

This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to XBRL International or XBRL organizations, except as required to translate it into languages other than English. Members of XBRL International agree to grant certain licenses under the XBRL International Intellectual Property Policy (https://www.xbrl.org/legal).


The attention of users of this document is directed to the possibility that compliance with or adoption of XBRL International specifications may require use of an invention covered by patent rights. XBRL International shall not be responsible for identifying patents for which a license may be required by any XBRL International specification, or for conducting legal inquiries into the legal validity or scope of those patents that are brought to its attention. XBRL International specifications are prospective and advisory only. Prospective users are responsible for protecting themselves against liability for infringement of patents. XBRL International takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Members of XBRL International agree to grant certain licenses under the XBRL International Intellectual Property Policy (https://www.xbrl.org/legal).