On Thu, Dec 01, 2016 at 11:07:45AM +0100, Bert Freudenberg wrote:
> 
> I agree basing it on UTC makes more sense, but I'm not sure how much code
> would need to change, and if some stored datetimes would be affected.
> 

Indeed, changing the instance variable format for DateAndTime does require the
ability to deserialize old instances that may have been stored in the snapshot.bin
of an MCZ file.

I just added this to the UTCDateAndTime project on squeaksource.com:

   Name: Chronology-Core-dtl.24
   Author: dtl
   Time: 1 December 2016, 10:20:50.201532 pm
   UUID: 961522d3-4d2a-42e8-bafc-f4ee338542bf
   Ancestors: Chronology-Core-dtl.23
   
   Handle DataStream deserialization of old format DateAndTime by converting to
   the new format. This is required for reading instances that have been saved
   in the snapshot.bin of a Monticello MCZ archive. If deserializing the snapshot.bin
   works at all, then it must also handle the special case of DataAndTime instances
   that were serialized with the old DateAndTime instance format.

I think this handles the DataStream cases properly. Similar patches might be required
for MASerializer and Fuel.

Dave