Changes since...: full list of timezone_name values as returned by ServiceM8

Hi, I am looking for a complete list of the possible values of timezone_name. I would also like to find out when the timezone_name field was added to the ServiceM8 API.

This is regarding https://developer.servicem8.com/v1.0/reference#get-vendor-single

Also, how does ServiceM8 treat the last-edit time stamp when daylight savings happens? Does the ServiceM8 clock stay on standard time, or switch in the middle of the night on a state by state basis for each vendor? Are those timing rules available anywhere in the ServiceM8 API ?