udunits/src/main/java/ucar/units/PrefixSymbol.java
public final int
    compareTo(Object obj)
    {
	String	thatID = ((PrefixSymbol)obj).getID();
	int	comp = thatID.length() - getID().length();
	if (comp == 0)
	    comp = getID().compareTo(thatID);
	return comp;
    }
public final int
    compareTo(Object obj)
    {
	String	thatID = ((PrefixSymbol)obj).getID();
	int	comp = thatID.length() - getID().length();
	if (comp == 0)
	    comp = getID().compareTo(thatID);
	return comp;
    }
Compares this prefix against another PrefixSymbol.  The sort keys are
decreasing length (major) and increasing lexicality (minor).
@param obj		The other PrefixSymbol.
@return			A negative value, zero, or a positive value
depending on whether this PrefixSymbol is less
than, equal to, or greater than <code>
obj</code>, respectively.