2.2.5 Content Negotiation

The client SHOULD request that the server provide a copy of the XML feed that will validate against the highest schema version that the client is able to process.<7> The client MUST do this by requesting a specific schema version in an HTTP Accept header ([RFC7231] section 5.3.2). The header MUST specify a media-range of "application\x-msts-radc+xml" and MUST specify an accept-extension parameter named "radc_schema_version" with a value of either "1.1" or "2.0". For example: "radc_schema_version=2.0" requests schema versions 2.0 and 2.1.

The server SHOULD support content negotiation.<8> If the server does not support content negotiation, or if the client does not request a specific schema version, the server MUST provide a copy of the XML feed adhering to schema version 1.1. If the server supports content negotiation but does not recognize the requested schema version, it SHOULD provide a copy of the XML feed adhering to schema version 1.1.