Block identifier, as the block height or block hash.
^0[xX][0-9a-fA-F]{1,64}$|[0-9]{1,12}
GET /coretime/regions HTTP/1.1 Host: dot-playbook.nownodes.io Accept: */*
successful operation
{ "at": { "hash": "text", "height": "text" }, "regions": [ { "core": "text", "begin": "text", "end": "text", "owner": "text", "paid": "text", "mask": "text" } ] }