code: function tms2zxy(zxys) {
          return zxys.split(',').map(function(tms) {
              var zxy = tms.split('/').map(function(v) { return parseInt(v, 10); });
              zxy[2] = (1 << zxy[0]) - 1 - zxy[2];
              return zxy.join('/');
          });
      }
docs: Converts MBTiles native TMS coords to ZXY.