@taldcroft, @eteq - at some level I was torn between what you both suggest, on the one hand feeling that it would be good to hide the actual number behind a descriptive name, on the other liking the general philosophy that a negative status can be counted on being "bad news".  I'm not quite sure what would be the benefit of strings, unless they're about as long as the above names, but then it would be a bit of overkill to hand those back (for timing work, the Time arrays can easily become substantial).