All, while writing a log file parser which parses log entries with nano-second timestamps I hit the following issue: Time instances can handle times down to nanosecond level. So something like this t := Time hour: 12 minute: 34 second: 56 nanoSecond: 1. is valid and works w/o problems. However DateAndTime and subclasses are not able to deal with Time instances whose nanoCount is ~= 0. E.g. the following fails: dt := DateAndTime date: Date today time: t. ts := TimeStamp date: Date today time: t. I've opened an issue for this: http://code.google.com/p/pharo/issues/detail?id=1487 CU, Udo