It's redefining the offsets from UTC for the zones, for standard time. And also repeals all of 15 USC 260a http://uscode.house.gov/view.xhtml?req=(title:15%20section:2... a.k.a. Section 3 of the Uniform Time Act of 1966. Ergo, the 'D' in all the time zones goes away.
Original text for the zones: http://uscode.house.gov/view.xhtml?req=(title:15%20section:2...
Bill amending that law: https://www.congress.gov/bill/117th-congress/house-bill/69/t...
It's redefining the offsets from UTC for the zones, for standard time. And also repeals all of 15 USC 260a http://uscode.house.gov/view.xhtml?req=(title:15%20section:2... a.k.a. Section 3 of the Uniform Time Act of 1966. Ergo, the 'D' in all the time zones goes away.