visad/src/main/java/ucar/nc2/iosp/grid/GridVariable.java
public GridRecord findRecord(int ens, int time, int level) {
    if (hasEnsemble()) {
      return recordTracker[ens * (ntimes * nlevels) + (time * nlevels) + level];
    } else {
      return recordTracker[time * nlevels + level];
    }
  }
public GridRecord findRecord(int ens, int time, int level) {
    if (hasEnsemble()) {
      return recordTracker[ens * (ntimes * nlevels) + (time * nlevels) + level];
    } else {
      return recordTracker[time * nlevels + level];
    }
  }
Find the grid record for the time and level indices
Canonical ordering is ens, time, level
@param ens   ensemble index
@param time  time index
@param level level index
@return the record or null