Versioning and deprecation

The path version (/v1) changes only for incompatible changes to the operations it keeps; additive changes — new fields, new operations, new optional parameters — ship without a path change and bump this document's info.version. A deprecated operation is flagged deprecated: true, answers every request with a Deprecation header (RFC 9745, the date the replacement shipped) and a Link header pointing at the replacement's documentation, and keeps working until a removal date is announced as a Sunset header. No operation is deprecated today.

An operation can also be withdrawn: removed from this document and from the API, with its removal recorded on the changelog and the document's major version raised. Withdrawal is reserved for operations Delpha stops offering altogether, and it does not change the path version, because the operations that remain are unaffected.