Table Constraints reaches Recommendation!
The Table Constraints specification became a full XBRL International Recommendation on 10 September 2026, completing work carried out by the Open Information Model Working Group over the past two years.
The specification builds on xBRL-CSV, which allows very large volumes of data to be reported as plain spreadsheet-style files, accompanied by a compact metadata file that explains what each column means. Table constraints let taxonomy authors add simple rules into that same metadata: which columns must be completed, what sort of value each one may contain, which combinations of values must be unique, whether a value must match an entry somewhere else in the report, and how many rows or tables are permitted.
Because most (although not all) of these constraints concern a single row at a time, software can validate a report as it reads it, using very little memory, and can spread the work across several processors if volume requires it. For the granular banking and insurance collections that now run to millions of rows, checks of this kind can be performed a great deal faster than was previously practical, and errors in structure can be reported before the heavier business rules are applied at all.
Table Constraints don’t replace XBRL Formula, which continue to permit the creation of more complex business rules. Instead it offers collectors a sensible and hugely efficient first layer to constrain the shape of data being ingested (as it says on the tin). Existing xBRL-CSV reports are unaffected, since constraints apply only where they have been defined.
Reaching Recommendation required several independent software implementations to pass conformance testing. Now that the specification has been finalised there will be a “sunrise” period for software vendors that would like to submit their software for XBRL International certification.
Assistance for taxonomy authors, including a formal requirements document, a primer and the conformance suites are available alongside the specification. There are also introductory guidance materials. You can find the specification on the XBRL International website. Go to it!
