-Default BASE_CODENAME is bullseye. Default ARCH is 64. The script expects corresponding
-$BASEFILE_DIR/${UPCASED_BASE_CODENAME}${ARCH}.tar.(gz|xz) to exist, and it must have been
+Default BASE_CODENAME is bookworm. Default ARCH is 64. The script expects corresponding
+$BASEFILE_DIR/${UPCASED_BASE_CODENAME}${ARCH}.tar.(zst|xz) to exist, and it must have been