cdm/src/main/java/ucar/nc2/dataset/CoordinateSystem.java
private CoordinateAxis lesserRank( CoordinateAxis a1, CoordinateAxis a2) {
    if (a1 == null) return a2;
    return (a1.getRank() <= a2.getRank()) ? a1 : a2;
  }
private CoordinateAxis lesserRank( CoordinateAxis a1, CoordinateAxis a2) {
    if (a1 == null) return a2;
    return (a1.getRank() <= a2.getRank()) ? a1 : a2;
  }
private CoordinateAxis lesserRank ( CoordinateAxis a1 , CoordinateAxis a2 ) { if ( a1 == null ) return a2 ; return ( a1 . getRank ( ) <= a2 . getRank ( ) ) ? a1 : a2 ; }
prefer smaller ranks, in case more than one
prefer smaller ranks in case more than one