FDA’s June 2026 conformance guide says a custom domain should be used only after confirming the data do not fit an existing domain, with implementation described in the clinical Study Data Reviewer’s Guide.
ReviewedEvidence1 sourceSectionWriting & Style
Quick answer
Before creating a custom domain, confirm the data cannot be represented in an existing standard domain, follow the applicable implementation guide, and document the custom implementation in the reviewer’s guide.
Key details
Core IssueFDA’s June 2026 conformance guide says a custom domain should be used only after confirming the data do not fit an existing domain, with implementation described in the clinical Study Data Reviewer’s Guide.
Registerscholarly, professional, or research/report writing
Important caveats
Scope Boundary
This is current FDA technical-conformance guidance for electronic study-data submissions; recheck the current FDA guide, supported standards, Data Standards Catalog, and eCTD specifications before relying on version-sensitive requirements.
Further guidance
Content
Current FDA guidance treats custom domains as an exception to use after existing-domain fit has been checked, not as a first-choice container for nonstandard data.
Purpose
Before creating a custom domain, confirm the data cannot be represented in an existing standard domain, follow the applicable implementation guide, and document the custom implementation in the reviewer’s guide.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
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