I want to know the answer to the following question:
In addition to calendaring programs, what kind of programs were most impacted by the changes?
All the background I'm provided with is that "For example, the 2007 change to DST rules in North America required many computer systems to be upgraded, with the greatest impact on email and calendaring programs; the upgrades consumed a significant effort by corporate information technologists.". Is that enough to answer the question?
Answer: yes