Wow, never knew that. Always just used EST, CST, MST or PST
Yep, for those states that go into daylight savings time, you use EDT, CDT, etc. until the time changes back to standard, then it is EST, CST, and so on.
(Off topic) I used to work with a gal for whom part of her responsibility was to set telephone appointments with existing clients in various states throughout the US. She NEVER could figure out the time zones and then when you threw in whether it was Daylight or Standard, she just about went nuts. It was frustrating to hear her trying to set a time with the clients.... (Sometimes I helped her.)