Open Information Model 1.0

Candidate Recommendation 06 May 2020

Copyright © XBRL International Inc., All Rights Reserved.

This version:
Paul Warren, XBRL International Inc. <>
Herm Fischer, Mark V Systems Limited <>
Mark Goodhand, CoreFiling <>
Daniel Dracott, CoreFiling <>
Eleanor Joslin, CoreFiling <>


Circulation of this Candidate Recommendation is unrestricted. This document is normative. Other documents may supersede this document. Recipients are invited to submit comments to, and to submit notification of any relevant patent rights of which they are aware and provide supporting documentation.


This document describes a syntax-independent model for business reports that conform to the XBRL v2.1 and XBRL Dimensions v1.0 specifications. The model is intended to enable easy and lossless transformation of a well defined set of semantics between a variety of different syntactic representations, including the XML syntax defined in the above specifications.

Table of Contents

1 Introduction
1.1 Scope
1.2 Terminology
1.2.1 Collections
1.3 Namespaces and namespace prefixes
2 Processors
3 XBRL Report Model
3.1 Datatypes
3.2 Reports
3.3 Facts
3.4 Dimensions
3.5 Links
3.5.1 Footnotes The xbrl:note concept
4 Prefixed content
5 Equality and equivalence
5.1 Equality definitions
5.1.1 URI comparison
5.2 Equivalence definitions


A References
B Intellectual property status (non-normative)
C Document History (non-normative)
D Errata Corrections incorporated in this document


1 Namespaces and namespace prefixes


Concept Core Dimension (Component)
Conformant processor
Core Dimension
Entity Core Dimension (Component)
Enumeration fact
Equal dimension value
Equal fact property
Equal facts
Equal reports
Equivalent fact property
Equivalent facts
Equivalent reports
Fact (Component)
Fact datatype
Fact period type
Language Core Dimension (Component)
Link group (Component)
Non-numeric fact
Non-text fact
Note ID core dimension (Component)
Numeric fact
Period Core Dimension (Component)
Prefixed content
Report (Component)
Supported specification
Taxonomy-defined Dimension (Component)
Text fact
Unit Core Dimension (Component)
Unordered collection
Validating conformant processor
XHTML fragment

Error codes

xbrle:invalidPeriodDimension 2
xbrle:misplacedNoteFactDimension 2

1 Introduction

The XBRL v2.1 [XBRL 2.1] and XBRL Dimensions v1.0 [DIMENSIONS] specifications define an XML-based syntax for business reports, and accompanying metadata definitions known as taxonomies. It is appealing to work with XBRL data in a variety of different formats such as JSON, relational and other databases and CSVs. Such use is hampered by the lack of a clear definition of the information that may be considered significant in an XBRL report, as distinct from that which is syntactic detail. This leads to inconsistencies in the data that is understood and how it is represented, and often to the exposure of unnecessary syntactic detail to end users.

This specification defines a syntax-independent model for an XBRL report, which allows different syntactic formats to be used to represent the same data. The model captures a subset of the information that can be represented in the XML syntax defined by XBRL v2.1, in order to provide a simple and portable model.

1.1 Scope

This document provides a model for an XBRL report (or XBRL instance) that conforms to the set of supported specifications. It does not attempt to model the metadata information defined in an XBRL taxonomy. The Working Group recognises the importance of taxonomy information when working with XBRL data, but believes that there is considerable value in a model that is restricted in scope to XBRL report on its own, and thus has chosen to address this requirement first.

Taxonomy information is expected to form the basis of future specifications that expose such information either in a separate model, or as layers of additional information that augment the model defined in this specification.

The supported specifications are:

1.2 Terminology

The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, in this specification, are to be interpreted as described in [IETF RFC 2119].

The keywords concept, fact, footnote, and taxonomy, as well as the terms nillable and abstract as applied to concepts, are to be interpreted as described in the XBRL specification [XBRL 2.1].

The keywords dimension, hypercube, typed dimension, explicit dimension and dimension default are to be interpreted as described in the XBRL Dimensions specification [DIMENSIONS].

The keywords time interval, local time and zone designator are to be interpreted as defined in ISO 8601 [ISO8601].

1.2.1 Collections

This specification uses the following terms to refer to collections. The use of these terms indicates whether the order and uniqueness of members is significant under the model, and thus whether these properties need to be preserved when transforming reports.

A list is an ordered sequence of members. Members may be repeated within the list.

An unordered collection is a collection that may contain repeated members. The number of times that each member appears is significant, but the order between them is not. Also known as a bag or multi-set.

A set is an unordered collection that contains no repeated members.

1.3 Namespaces and namespace prefixes

Namespace prefixes [XML Names] will be used for elements and attributes in the form ns:name where ns is the namespace prefix and name is the local name. Throughout this specification, the mappings from namespace prefixes to actual namespaces are consistent with Table 1.

The prefix column in Table 1 is non normative. The namespace URI column is normative.

Table 1: Namespaces and namespace prefixes
Prefix Namespace URI

The prefix dtr-type denotes any namespace that is the namespace for a type defined in the Data Types Registry [DTR STRUCTURE].

2 Processors

This specification defines two classes of processors:

3 XBRL Report Model

The report model is defined as a series of components, each having a set of named properties. These components, and their associated properties are defined in the tables shown below. Components may also have constraints associated with them which all instantiations of these components must adhere to.

3.1 Datatypes

The report model uses the XML Schema datatypes system [XML Schema Datatypes] for defining the datatype of values. It does not make use of the XML Schema structures system [XML Schema Structures], as this does not make sense outside of the context of an XML document.

Values in the report model refer to the value within the value space. The lexical representation does not form part of the model.

For example, 1, 1.0 and 1.00 are all alternative lexical representations of the same xs:decimal value. An OIM processor must treat all these values as equal, and is not required to retain the lexical representation from which the value was obtained.

It should be noted that there are some references in this document to XBRL "item types", such as dtr-type:domainItemType. References to these item types are primarily to identify classes of facts, based on their datatypes.

Item types are technically XML schema complex types, as they contain definitions of allowed XML attributes. These attribute definitions are not applicable to the report model, and values in the report model are only required to comply with the "simple content" portions of these datatypes (see complex type definitions with simple content [XML Schema Structures]).

3.2 Reports

The top-level component is a report.

Component: Report
A list of URLs to XML Schema document that together identify the taxonomy for the report. The list MUST NOT be empty (xbrle:noTaxonomy).

A set of facts.


An optional URL recording the location from which the report was loaded (or an explicitly specified alternative base URL). This URL MAY be used for resolving relative URLs appearing as fact and dimension values within the report, although such resolution will depend on the definition of the concepts and dimensions involved and is not prescribed by this specification.

This model simplifies the mechanism for identifying a taxonomy to a list of references to XML Schema documents. The xBRL-XML syntax permits references to both schema and linkbase files, and also references in the form of links to the definition of role and arcrole types. References to linkbases are not supported, and <roleRef> and <arcroleRef> in the xBRL-XML syntax are subject to special treatment. See [xBRL-XML] for full details.

3.3 Facts

Component: Fact
A fact is a discrete piece of information in an XBRL Report. All facts have the following properties.

A unique identifier for the fact. The value MUST be an NCName (xbrle:invalidFactId), and MUST be unique across all facts within the report (xbrle:duplicateFactId). This property MUST be present on all facts (xbrle:missingFactId).

{id} attributes can be useful in providing traceability of facts through different syntactic representations, but do not form part of the semantic information provided by a report.

A set of dimensions. The set may contain at most one of each core dimension. The set may contain multiple taxonomy defined dimensions, but their {name} properties MUST be unique within the set xbrle:duplicateFactDimension.
A set of link groups associated with the fact.
The value associated with this fact. This may be the special value "nil". The meaning of a fact reported as "nil", the distinction between this and a fact that is not reported, or a fact reported with an empty, or zero, value (where applicable) is implementation dependent.
The precision of the value, expressed as a number of decimal places, or "infinity", indicating that the value is infinitely precise.

If the fact's {value} is "nil", the fact MUST be nillable; otherwise, the {value} MUST be in the value space of the fact's datatype (xbrle:invalidFactValue).

The {decimals} property MUST be present on, and MUST only be present on, numeric facts (xbrle:misplacedDecimalsProperty).

A fact's datatype is the XML Schema type of the concept identified by the fact's concept core dimension.

A fact is nillable if the concept identified by the fact's concept core dimension is nillable.

A numeric fact is a fact with a datatype that is derived from the XML Schema types of xs:decimal, xs:double or xs:float.

A non-numeric fact is any fact that is not a numeric fact.

A text fact is a fact with a datatype that is derived from the XML Schema type of xs:string, but which is not one of, or a type derived from one of, the following types:

  • xs:language
  • xs:Name
  • dtr-type:domainItemType
  • dtr-type:noLangTokenItemType
  • dtr-type:noLangStringItemType

A non-text fact is any fact that is not a text fact.

An enumeration fact is a fact with a concept core dimension that identifies an enumeration concept. An enumeration fact has a value that is either a single expanded name or a set of expanded names.

Note that in the above definitions, "derived from" includes indirect derivation via intermediate types.

The text fact definition identifies those facts to which the language core dimension is applicable.

3.4 Dimensions

A dimension is a piece of additional information that serves to uniquely identify a fact. A dimension may either be one of the core dimensions listed below or a taxonomy-defined dimension.

A core dimension is a dimension that is defined by the XBRL v2.1 specification, as distinct from those which are defined in a taxonomy using the XBRL Dimensions specification [DIMENSIONS] .

Component: Concept Core Dimension
The expanded name corresponding to xbrl:concept
An expanded name identifying an XBRL concept.

The concept core dimension MUST be present on all facts (xbrle:missingConceptDimension).

The concept core dimension MUST identify a concept from the taxonomy (xbrle:unknownConcept).

The identified concept MUST NOT be abstract (xbrle:valueForAbstractConcept).

Component: Entity Core Dimension
The entity core dimension represents the primary legal entity (person or organisation) associated with a fact.
The expanded name corresponding to xbrl:entity
A URI denoting the scheme from which an identifier is drawn.
A string identifying the entity to which the fact relates.

The entity core dimension MUST NOT have a scheme of '' with an identifier of 'NA'.

The entity core dimension is optional, and MAY be omitted if there is no primary legal entity associated with a fact, either because the fact does not relate to a legal entity, or because the fact captures a transaction or relationship between two or more legal entities with equal standing.

As defined in [xBRL-XML], the special entity with scheme of '' and identifier 'NA' is used to represent the absence of this dimension in xBRL-XML syntax.

Component: Period Core Dimension
The period core dimension represents the period of time, or instant, to which a fact is applicable. Whilst the xBRL-XML representation uses different elements to represent instants and durations, this specification uses a common model for both in the form of an time interval as defined in ISO 8601 [ISO8601], with instants being represented using a zero-length time interval.
The expanded name corresponding to xbrl:period
A time interval, as defined in ISO 8601. The time interval MAY be zero-length (i.e. start and end at the same instant), denoting an instant in time. The time interval MAY be defined in local time (i.e. without a time zone designator) in which case processors MUST NOT assume a particular time zone, but MUST preserve the information that the time interval is in local time.

This specification, being a syntax-independent model, does not make use of the representations defined in ISO 8601, but as ISO 8601 is the representation used in xBRL-XML and in other representations based on this specification, the model draws on the terms and definitions used in ISO 8601 in order to ensure that the {interval} property can be represented using formats defined in ISO 8601.


If the fact's period type is duration, the period code dimension is optional, and if present {interval} MUST be a non-zero length time interval (xbrle:invalidPeriodDimension).

If the fact's period type is instant, the period code dimension MUST be present (xbrle:missingPeriodDimension) and {interval} MUST be a zero-length time interval (xbrle:invalidPeriodDimension).

Note that as defined in [xBRL-XML], the absence of the period core dimension is represented by the special value of "forever" in xBRL-XML syntax.

A fact's period type is the value of the @periodType attribute on the schema definition of the concept identified by the fact's concept core dimension, and is either duration or instant.

Component: Unit Core Dimension
The expanded name corresponding to xbrl:unit
An unordered collection of expanded names, identifying individual measures.
An optional, unordered collection of expanded names, identifying individual measures.

The unit core dimension MUST only be present on numeric facts (xbrle:misplacedUnitDimension). The unit core dimension is optional on numeric facts.

The unit core dimension MUST NOT have a single numerator of xbrli:pure with no denominators (xbrle:illegalPureUnit). The xbrli:pure measure used in xBRL-XML is mapped to a fact with an absent unit core dimension in this model (see [xBRL-XML]).

Component: Language Core Dimension
The expanded name corresponding to xbrl:language
The language in which the fact is reported. Languages MUST be representable as using a valid BCP 47 [BCP47] language code xbrle:invalidLanguage.

The language core dimension MUST only be present on text facts (xbrle:misplacedLanguageDimension) and is optional on such facts.

Component: Note ID core dimension
The note ID core dimension is used on xbrl:note facts in order to prevent multiple occurrences of such facts in a report from being classified as duplicates. xbrl:note facts are used to represent text footnotes (see Section
The expanded name corresponding to xbrl:noteId
A unique identifier for a fact.

The {id} property MUST be the same as the fact's {id} property (xbrle:invalidNoteIDValue).

This dimension MUST NOT be present on facts with a concept core dimension that is not xbrl:note (xbrle:misplacedNoteIDDimension).

See also Section

Component: Taxonomy-defined Dimension
The expanded name identifying the dimension.
The value for the dimension. Values for taxonomy-defined dimensions do not have any associated language information.

The {name} of a taxonomy-defined dimension MUST identify a dimension in the taxonomy (xbrle:unknownDimension).

If the identified dimension is an explicit dimension, the {value} MUST be a valid expanded name; otherwise, if {value} is the special value "nil", the typed dimension MUST be nillable; otherwise, {value} MUST be in the value space for the datatype of the typed dimension (xbrle:invalidDimensionValue).

Explicit dimensions will have a datatype of xs:QName, but it should be noted that a datatype of xs:QName does not imply that the dimension is explicit; it may be a QName typed dimension. The actual nature of the dimension can be determined from the taxonomy.

The set of taxonomy-defined dimensions associated with a fact does not include any explicit dimensions using a dimension default.

3.5 Links

Links represent relationships between facts in a report. Links are a generalisation of the footnote mechanism defined in XBRL v2.1.

Component: Link group
A link group is a collection of relationships between facts in a report. The group is uniquely identified by the combination of the {group} and {link type} properties. The relationships in a link group have a common source fact, which is the fact on which the link group is defined. The target facts for the relationships are defined by the {target facts} property.
A URI identifying a grouping of links between facts.
{link type}
A URI identifying the type of the relationships between the facts in the group.
{target facts}
A list of facts which are the target of the links in the group.

3.5.1 Footnotes

This specification prescribes special behaviour for the standard link type of The {target facts} for any link group with this {link type} MUST have a concept core dimension of xbrl:note (xbrle:illegalStandardFootnoteTarget).

The mapping between links and footnotes as defined in XBRL v2.1 is described in xBRL-XML [xBRL-XML]. The xbrl:note concept

This specification defines the xbrl:note concept, which is used to represent text footnotes as defined in XBRL v2.1, and for which specific handling is prescribed in xBRL-XML [xBRL-XML]. The xbrl:note concept has a datatype of xbrli:stringItemType.

The value of the xbrl:note concept MUST be a string containing a serialisation of an XHTML fragment (xbrle:invalidXHTMLFragment). The serialisation assumes a default namespace of, and any elements in that namespace MUST use the default namespace (xbrle:xhtmlElementInNonDefaultNamespace).

An XHTML fragment is an XML fragment in which any top-level element nodes are in the namespace.

Facts with a concept core dimension of xbrl:note:

Note that as text facts, xbrl:note facts cannot have the {decimals} property or unit core dimension.

4 Prefixed content

Some datatypes make use of prefixes as a shorthand notation for namespace URIs. Values for these datatypes make use of a map of prefix to namespace URI bindings that are in scope for the location in which the value appears. Neither the prefixes, nor the maps to which they refer form part of the model, and as such, special handling of these values is required in order to ensure that the model contains the referenced URIs rather than prefixes. Values for which this is required are referred to as prefixed content..

In an XML document, the map of prefixes to namespace URIs is provided by namespace bindings (see [XML Names]). Other formats based on this model typically use a prefix map.

Under this model, prefixed content is the value of any fact or taxonomy defined dimension with a datatype of, or derived from:

  • xs:QName
  • xbrli:QNameItemType
  • dtr-type:SQNameType
  • dtr-type:SQNameItemType
  • dtr-type:SQNamesType
  • dtr-type:SQNamesItemType

5 Equality and equivalence

This specification provides separate definitions of equality and equivalence for facts and reports. Equivalent reports can be considered to convey the same semantic information. The stricter definition of equal reports additionally requires fact {id} properties to be equal.

5.1 Equality definitions

Two reports, A and B, are equal under this model if:

  • For every fact in A, there is an equal fact in B, and vice versa; and
  • The {taxonomy} component of A is equal to the {taxonomy} component of B.

Two facts, a and b, are equal if, for each property present on a, there is an equal fact property present on b and vice versa.

Two fact properties are equal if they meet the relevant criterion defined below:

  • Two {id} properties are equal if they have the same string value.
  • Two {dimensions} properties, a and b, are equal if, for every dimension in a the same dimension is present in b with an equal dimension value and vice versa.
  • Two {value} properties are equal if they are both "nil" or they have the same actual value based on the facts' datatype (see also Section 5.1.1).
  • Two {decimals} properties are equal if they have the same integer value.
  • Two {links} properties, a and b, are equal if, for every link group in a there is a link group in b with the equal {group}, {link type} and {target facts} properties, and vice versa. Two {target fact} properties, tfa and tfb are equal if each fact in tfa is equal to the corresponding fact in tfb.

Two dimension values are equal if they meet the relevant criterion defined below:

5.1.1 URI comparison

Values for datatypes of, or derived from, xs:anyURI that are relative URIs are not absolutized prior to comparison. This means that two relative URIs with same value will be considered equal even though they appear in different documents with different locations. This specification does not specify where relative URIs appearing in fact and taxonomy-defined dimension values should be resolved relative to.

5.2 Equivalence definitions

Two reports, A and B, are equivalent under this model if, for every fact in A, there is at least one equivalent fact in B, and vice versa.

Two facts, a and b, are equivalent if, for each property on a, there is an equivalent fact property present on b and vice versa.

Two fact properties are equivalent if they meet the relevant criterion for equal fact properties with the following modifications:

  • Two {id} property values are always considered equivalent (i.e. they are ignored for the purposes of establishing equivalence).
  • Similarly, when considering the equivalence of {dimensions} properties, two note id core dimensions are always considered equivalent.
  • Facts in the {target facts} properties of each link group in the {links} properties need only meet the requirements of equivalent facts.

The above definition does not require equivalent reports to have the same number of facts. Multiple equivalent facts in one report can be considered equivalent to a single fact in the other.

Appendix A References

IETF. " BCP47: Tags for Identifying Languages "
XBRL International Inc.. "XBRL Dimensions 1.0"
Ignacio Hern√°ndez-Ros
, and Hugh Wallis.
XBRL International Inc. "Data Types Registry - Structure 1.1"
Mark GoodhandHugh WallisPaul Warren.

XBRL International Inc.. "Extensible Enumerations 2.0"
Mark Goodhand
, and Paul Warren.
IETF (Internet Engineering Task Force). "RFC 2119: Key words for use in RFCs to Indicate Requirement Levels"
Scott Bradner.

International Standards Organisation. " ISO 8601 international standard numeric date and time representations. "
XBRL International Inc.. "XBRL Open Information Model Common Definitions"
Herm Fischer
, Mark Goodhand, and Paul Warren.
XBRL 2.1
XBRL International Inc.. "Extensible Business Reporting Language (XBRL) 2.1 Includes Corrected Errata Up To 2013-02-20"
Phillip Engel
, Walter Hamscher, Geoff Shuetrim, David vun Kannon, and Hugh Wallis.
XML Names
W3C (World Wide Web Consortium). "Namespaces in XML 1.0 (Third Edition)"
XML Schema Datatypes
W3C (World Wide Web Consortium). "XML Schema Part 2: Datatypes Second Edition"
Paul V. Biron
, and Ashok Malhotra.
XML Schema Structures
W3C (World Wide Web Consortium). "XML Schema Part 1: Structures Second Edition"
Henry S. Thompson
, David Beech, Murray Maloney, and Noah Mendelsohn.
XBRL International Inc.. "xBRL-XML: XML Mappings for the Open Information Model 1.0"
Paul Warren
, and Herm Fischer.

Appendix B 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 (


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 (

Appendix C Document History (non-normative)

13 January 2016Paul Warren

First Public Working Draft

14 December 2016Paul Warren

Candidate Recommendation

02 May 2017Paul Warren

Second Candidate Recommendation

12 December 2018Paul Warren

Third Candidate Recommendation

12 June 2019Paul Warren

Fourth Candidate Recommendation

07 May 2020Paul Warren

Fifth Candidate Recommendation

Appendix D Errata Corrections incorporated in this document

This appendix contains a list of the errata that have been incorporated into this document. This represents all those errata corrections that have been approved by the XBRL International Specification Maintenance Working Group (SWG) up to and including 06 May 2020. Hyperlinks to relevant e-mail threads may only be followed by those who have access to the relevant mailing lists. Access to internal XBRL mailing lists is restricted to members of XBRL International Inc.

No errata have been incorporated into this document.