E.g. $ nix ls-store --json --recursive --store https://cache.nixos.org /nix/store/b0w2hafndl09h64fhb86kw6bmhbmnpm1-blender-2.79 \ | jq .entries.bin.entries.blender.narOffset 400
This is primary to allow hydra-queue-runner to extract files like "nix-support/hydra-build-products" from NARs in binary caches.