Download the current Define-XML v2.1 package from cdisc.org/standards/data-exchange/define-xml and note the version number (v2.1.11 or later as of mid-2026).
Set the DefineVersion attribute in your define.xml header to '2.1.0' (the specification version remains 2.1.0; the package version tracks CT updates).
Reference the Controlled Terminology package version date in the Standards section using the version date string from the published CT files, not the package number.
Validate the document against the define.xsl stylesheet and the define-enumerations schema file included in the downloaded package.
Run your define.xml through an independent validator (e.g., Pinnacle 21 or the CDISC conformance rules) before including it in a regulatory submission.
Known gotchas
Define-XML minor package versions (e.g., v2.1.10, v2.1.11) are schema/CT update packages, not new specification versions — the specification version declared in define.xml stays '2.1.0'; always use the latest package for the current CT definitions.
Each CT package update ships a new define-enumerations schema file; validating against an older schema version will produce false errors or miss newly added enumerations.
The FDA technical conformance guides reference the Define-XML v2.1 specification; confirm the specific package version accepted by your regulatory authority before finalizing a submission.
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