RFC: Timestamps/timezones proposal

[Stuart D. Gathman]

Charles Day wrote:
>> Under what circumstances would an end user ever choose the option "randomly
>> change the dates on my transactions when I change the timezone on my
>> machine"?
>>     
> Tell me how this proposal would cause "random" date changes. Only the
> *display* of the timestamp changes, and only according to settings that you
> pick yourself.
>   
The key is that the register would display date,time, AND TIMEZONE.  The 
timezone lets the user recognize that 11:23PM Jul 13, 2008 EDT is really 
the same as 03:23AM Jul 14, 2008 BST (or whatever - I didn't actually 
look up BST).  TIMEZONE is what disambiguates 2:00AM EDT from 2:00AM EST 
when the clock jumps back.  TIMEZONE is crucial data when using 
timestamps - even within a single time zone, if events in the wee hours 
are important.  I worked on a security guard monitoring system, and even 
though all events were within a single timezone, display had to include 
timezone to distinguish between EST/EDT.

If the register displays date only, but you want to store timestamps 
instead to keep timestamp functionality available, then you must store 
the timezone also - even in memory.  A timestamp without timezone is 
like Incredible without Frozone - no I mean you can't recover the date 
entered by the user.  Storing or hardwiring a fixed timezone for date 
only operation is acceptable if documented.