Daylight Savings Time Confusion

It is bad enough that some countries do not use daylight savings time, I found out today that the effective dates are not consistent across countries. I know in China they do not have daylight savings time. Since I need to contact friends there, I had to adjust the time difference from +16 hours to +15 hours starting this week. I also talk to a “student” twice a week in Ukraine. I know they use daylight savings time, but the beginning and ending dates are different. The US changed time this past Sunday, but Ukraine does not make the time change until March 31. So, I have a standing call at 9:00 am Pacific, which is 7:00 pm in Kyiv. Since I did not know about the time discrepancy, I thought Vitalii was late when in fact I was an hour early. For the next three weeks, I have to keep track of this difference when calling in to our meeting. Ugh.