SDLV meaning in Governmental ?

Shuttle-derived vehicle (SDV) is a term describing one of an array of concepts that have been developed for building space launch vehicles and spacecraft using the already developed components, technology, and infrastructure of the Space Shuttle program.

In the late 1980s and early 1990s, NASA formally studied a cargo-only vehicle, Shuttle-C, that would have supplemented the crewed Space Shuttle. In 2005, NASA was developing the Ares I and Ares V launch vehicles, based in part on highly modified Shuttle components, to enable exploration of the Moon and Mars. The agency also studied a third such vehicle, the Ares IV.

After the earlier programs were cancelled, NASA began development of the Space Launch System (SLS) in 2011. SLS is a super heavy-lift expendable launch vehicle. Its core stage is structurally and visually similar to the Space Shuttle external tank. Each SLS launch reuses and expends four of the pre-flown RS-25D engines that were de-mounted from the Space shuttles. SLS also uses a pair of solid rocket boosters derived from the Space Shuttle Solid Rocket Booster. The first SLS was delivered to Kennedy Space Center in 2021 for the Artemis 1 mission, and As of August 2021 the first launch will be no earlier than 22 November 2021.