This document is a public draft. Readers are invited to submit comments to the Implementation Guidance Task Force.
- 1 Introduction
- 2 Scope
- 3 Filing Rules
- 3.1 Rules related to the submission of reports
- 3.2 iXBRL-specific rules
- 3.3 Taxonomy references
- 3.4 Allowed standards and versions
- 3.5 XBRL formula rule results
- 3.6 XBRL content rules
- 3.7 Constraining built-in dimensions
- 4 Examples of rules to be avoided
- 4.1 Avoid restricting unused namespaces
- 4.2 Avoid restricting unused ID attribute facts
- 4.3 Avoid prescribing specific namespace prefixes
- 4.4 Avoid constraints that can be built into the taxonomy
- 4.5 Avoid imposing additional element order constraints
- 4.6 Avoid specifying naming conventions for context IDs and other identifiers
- 4.7 Avoid the use of XML comments and processing instructions to capture filing metadata
- 4.8 Avoid restricting unused contexts/units
- 4.9 Avoid restricting duplicated contexts/units
- 4.10 Avoid restating specification constraints
- 4.11 Avoid restricting syntax for reporting precision
- 5 Summary
Automated validation rules can play a key role in ensuring the quality of XBRL reports. Validation rules that are backed by requirements from the underlying business domain are referred to as business validation rules, whereas validation rules that are driven by the technical requirements and limitations of a filing system are referred to as filing rules.
XBRL best practice recommends minimising the use of filing rules as they create a burden for software developers and preparers and can create interoperability issues. A separate piece of guidance discusses the broad principles for creation and publication of filing rules.
This guidance provides a checklist of commonly found filing rules. It also provides examples of the types of rule that should not be included as filing rules. This checklist is intended to be used as a reference while defining filing rules for an XBRL reporting programme. This guidance is targeted towards XBRL and iXBRL report collectors.
The filing rules discussed in this document are provided as guidance only. Data collectors should consider whether each rule is necessary and applicable to their reporting system.
This guidance covers filing rules applicable for XBRL/iXBRL reports. The guidance is not intended to provide a comprehensive list of filing rules. The taskforce studied filing rules across XBRL programmes such as SBR (Netherlands), CRD IV (including a number of country-specific CRD IV implementations), HMRC (UK) and SEC (US).
This guidance does not cover filing rules that relate to extension taxonomies. The task force plans to cover this in the future as a separate piece of guidance.
3 Filing Rules
This section describes filing rules for different categories, such as those related to submission, use of Inline XBRL, report contents and built-in dimensions.
3.1 Rules related to the submission of reports
Restrictions are often placed on the format in which the filing is submitted.
3.1.1 Number of files
Requirements for the number of files in a submission vary by reporting environment. In an XBRL reporting environment, filing rules should specify the number of XBRL report files required. In an iXBRL reporting environment filing, rules should specify the number of Inline XBRL documents that can be included in an Inline XBRL document set. Filing rules may also specify the inclusion of other XBRL file types (for example, to require an extension taxonomy schema and linkbase) or other non-XBRL files.
3.1.2 File name suffixes
Filing rules should specify which suffixes are acceptable for use on submitted files. The Report Packages Working Group Note recommends:
.xbrlfor XBRL reports.
.htmlfor iXBRL reports.
.xhtml are also in common use for XBRL and iXBRL reports, respectively. It should be noted that the choice of suffix for iXBRL reports can influence how browsers will render the report.
Where an extension taxonomy is submitted alongside the report,
.xml should be used for schema and linkbase files respectively.
3.1.3 File naming
Filing rules may specify file naming conventions to ensure consistency. Any file naming conventions specified should be possible to validate automatically.
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