    (numeric) identifies the bit number as indicating acceptance and readiness for the named softfork rule
    ...
  },
  "capabilities" : [                       (json array)
    "str",                                 (string) A supported feature, for example 'proposal'
    ...
  ],
  "vbrequired" : n,                        (numeric) bit mask of versionbits the server requires set in submissions
  "previousblockhash" : "str",             (string) The hash of current highest block
  "transactions" : [     