793     struct Metadata : public Message::FooterData<Metadata>  struct in ot::Coap::CoapBase
795         Ip6::Address    mSourceAddress;            // IPv6 address of the message source.
796         Ip6::Address    mDestinationAddress;       // IPv6 address of the message destination.
797         uint16_t        mDestinationPort;          // UDP port of the message destination.
798 …ponseHandler mResponseHandler;          // A function pointer that is called on response reception.
799         void           *mResponseContext;          // A pointer to arbitrary context information.
800 …   TimeMilli       mNextTimerShot;            // Time when the timer should shoot for this message.
801         uint32_t        mRetransmissionTimeout;    // Delay that is applied to next retransmission.
802         uint8_t         mRetransmissionsRemaining; // Number of retransmissions remaining.
804         uint8_t mHopLimit; // The hop limit.
806         bool mAcknowledged : 1;  // Information that request was acknowledged.
807         bool mConfirmable : 1;   // Information that message is confirmable.
808         bool mMulticastLoop : 1; // Information that multicast loop is enabled.
810 …   bool mIsHostInterface : 1; // TRUE if packets sent/received via host interface, FALSE otherwise.
813         bool mObserve : 1; // Information that this request involves Observations.
816 …ckwiseReceiveHook  mBlockwiseReceiveHook;  // Function pointer called on Block2 response reception.
817 …ckwiseTransmitHook mBlockwiseTransmitHook; // Function pointer called on Block1 response reception.