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Understanding XBRL instance document

XBRL is XML for business reporting, with facts identified by taxonomy concepts and contexts. Read about XBRL 2.1, numeric units and report packages.

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An XBRL instance document is an XML file that holds the facts of a business report, such as revenue or total assets. Each item fact names a taxonomy concept and refers to a context identifying the entity and period. Numeric facts also refer to a unit, such as euros. XBRL 2.1, a Recommendation of XBRL International, defines the core format. Klarbon support is planned, not available yet.

What is in an XBRL instance?

Part Holds
xbrli:xbrl the root element
link:schemaRef the taxonomy entry point the report uses
xbrli:context entity identifier and period, an instant or a start and end date, with dimensions if any
xbrli:unit the unit of measure, such as iso4217:EUR or shares
Facts item fact elements named for taxonomy concepts, with contextRef; numeric items also use unitRef and accuracy attributes as their type requires
Footnotes optional notes linked to facts
Property Value
Syntax XML
Core specification XBRL 2.1, Recommendation of 31 December 2003, errata to 20 February 2013
Tables XBRL Dimensions
Business rules XBRL Formula
Report package .xbr for an XBRL report, .xbri for an Inline XBRL report

XBRL International publishes the specifications and the report package guidance (specifications, XBRL 2.1, report packages).

XBRL or iXBRL?

XBRL instance Inline XBRL
File XML XHTML page
Readable by people no, needs software yes, in a browser
Facts elements in the XML tags around text and numbers on the page
Used for supervisory and statistical reporting annual reports, tax returns, ESEF

What does Klarbon do with XBRL?

Opening an instance and showing its facts with the taxonomy labels is planned in Klarbon, not available yet. Klarbon does not file reports with any authority. Klarbon works with invoices and bank statements; see the invoice viewer.

Frequently asked questions

What is an XBRL instance document?

An XML file that holds the facts of a business report, such as revenue or total assets, in eXtensible Business Reporting Language. Each item fact points to a taxonomy concept and a context identifying the entity and period. Numeric items also refer to a unit.

What is an XBRL taxonomy?

The dictionary a report uses. It defines the concepts, their labels in one or more languages, and how they relate, for example that total assets is the sum of its parts. Regulators and standard setters publish taxonomies, such as the IFRS Accounting Taxonomy.

Is XBRL the same as iXBRL?

No. An XBRL instance is plain XML for software. Inline XBRL puts the same facts as tags inside an XHTML page people can read.

Can an XBRL file be read without its taxonomy?

Only partly. The numbers and dates are in the file, but what each concept means, its label and how it adds up are in the taxonomy, so a reliable reading needs both.

Sources

Updated 5 November 2026