code: @Pure
  	public static double toESRI_z(double z) {
  		if (Double.isInfinite(z) || Double.isNaN(z)) {
  			return ESRI_NAN;
  		}
  		return z;
  	}
docs: Translate a z-coordinate from Java standard
  to ESRI standard.
  
  @param z is the Java z-coordinate
  @return the ESRI z-coordinate