cdm/src/main/java/ucar/nc2/dataset/conv/GDVConvention.java
private String findAlias(NetcdfDataset ds, Variable v) {
    String alias = ds.findAttValueIgnoreCase(v, "coord_axis", null);
    if (alias == null)
      alias = ds.findAttValueIgnoreCase(v, "coord_alias", "");
    return alias;
  }
private String findAlias(NetcdfDataset ds, Variable v) {
    String alias = ds.findAttValueIgnoreCase(v, "coord_axis", null);
    if (alias == null)
      alias = ds.findAttValueIgnoreCase(v, "coord_alias", "");
    return alias;
  }
look for an coord_axis or coord_alias attribute