Hi, I traced a bug when working with timespans to the following issue illustrated in the code snippet below. The last expression in the snippet yields false, although it should yield true (imho). |start end span| start :=DateAndTime now. end := start + 1 hour. span := Timespan starting: start ending: end. (span intersection: span) = span --> false I think that the intersection of a span with itself, should be itself. The origin of the problem is that Timespan>>intersection: creates a new timespan roughly as follows: Timespan starting: aBegin ending: self end. But Timespan>>end returns the end time of the timespan minus the clockprecision. As such, the intersecting span is a nanosecond shorter than the one we would expect. This eventually yields wrong results when working with timespans. The real question now is: should the implementation of Timespan>>intersection be changed -or- should Timespan>>end really return the (non-included) end time (that was passed when constructing it)? I sent this email to bugs@chronos-st.org, but a discussion here probably will not hurt either. Best regards Johan Brichau