While we're talking about Chronology:

I found it very odd that the following assertion does not hold:

|x y|
x := self someDateAndTime.
y := self someOtherDateAndTime.
span := Timespan starting: x ending: y.
self assert: span end = y.

Instead, #end returns a DateAndTime that is one nanosecond before y.  
Now, I understand the intent here, but given the method names it's 
counter intuitive, and in practice it means that I never use #end but 
instead use "span next start", which I have found gives me the value I 
was expecting.   Maybe it's just me, but I prefer to (for example) 
print timespans as "1:00 pm - 2:00 pm" rather than "1:00 pm - 
1:59:59.999999999 pm".

Thoughts?

Avi