ST2110SdpOverrides

Per-sender SDP attribute overrides. Each field, when non-empty, replaces what Norsk would otherwise auto-generate. Use these for deployments where the controller / receivers expect a specific SDP value Norsk can’t infer from its own state — e.g. an explicit ts-refclk:ptp=<version>:<gmid>:<domain> pointing at a different grandmaster, or a non-default mediaclk shape.