public FileFlatField(FileAccessor accessor, CacheStrategy strategy) throws VisADException {
    super(accessor.getFunctionType(), getNullDomainSet(accessor.getFunctionType().getDomain()));

    fileAccessor = accessor;
    cacheStrategy = strategy;

    // '0' is in legal range of adaptedFlatFieldIndex,
    // but not owned by this
    adaptedFlatFieldIndex = 0;
  }