static private boolean isAbrv(String a){

		Converter[] u;
		String t = getTypeFromUnit(a);
		if (t == "vol")
			u = volUnits;
		else if ( t == "pressure")
			u = pressureUnits;
		else // assume weight
			u = weightUnits;

		for (int i=0; i<u.length; i++){
			if (u[i].abrv.equalsIgnoreCase(a))
				return true;

		}
		return false;

	}