typedef struct { ... } SilcID;

    The generic ID structure that can represent SilcClientID, SilcServerID
    and SilcChannelID.  The silc_id_payload_parse_id returns the ID in the
    SilcID structure.  Other routines except either SilcClientID,
    SilcServerID or SilcChannelID as a void pointer.

    typedef struct SilcIDStruct {
      union {
        SilcServerID server_id;
        SilcChannelID channel_id;
        SilcClientID client_id;
      } u;
      SilcIdType type;
    } SilcID;