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conformance · v146

v146 · data-url-mime-type-parameter-preservation — conformance probe

8 assertions drawn from the spec. Each is a single contract the spec text makes. Pass/fail reflects what this browser executed; blocked means the contract was not run because it needs user mediation, hardware, or another unavailable precondition. Open the page in Chrome stable / canary / Firefox / Safari to compare.

browser: spec: https://fetch.spec.whatwg.org/#data-url-processor chromestatus: #4874471565557760 generated 2026-06-06T15:28:01Z by codex-devtools-mcp
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id contract kind verdict detail
fetch-data-url-preserves-charset-param Fetching a data: URL with a charset parameter exposes that parameter on the response's Content-Type header. script
fetch-data-url-preserves-custom-param Non-charset MIME parameters (e.g. boundary, profile) on a data: URL are preserved on the response Content-Type rather than dropped. script
fetch-data-url-preserves-multiple-params Multiple MIME parameters on a single data: URL are all preserved after MIME serialization. script
fetch-data-url-default-mime-still-text-plain A data: URL without an explicit MIME type still defaults to text/plain;charset=US-ASCII per the Fetch spec. spec ↗ script
fetch-data-url-base64-payload-decoded A base64-encoded data: URL with a MIME parameter still decodes its payload correctly while preserving the parameter. script
fetch-data-url-preserves-profile-param A profile parameter on an application/calendar+xml data: URL is preserved, not reduced to a bare MIME essence. script
fetch-data-url-preserves-encoded-param-value Percent-encoded delimiter characters inside parameter values remain part of the serialized MIME parameter value. script
fetch-data-url-preserves-iso-8859-1-charset An ISO-8859-1 charset parameter on a text/csv data: URL is preserved alongside other MIME parameters. script