Then somebody change the timezone database rules: %America/Montreal, 1349110800% → ---Oct 1st, 13:00 EDT--- %America/Montreal, 1349110800% → *Oct 1st, 12:00 EST* ☹

You can store it as: %America/Montreal, 2012 10 1 13 0 0% → Oct 1st, 13:00 EDT That however, changes the original point in time...