Not always the slot name: the CSR label arrays are label_offsets /
label_bytes on disk. Lives here rather than in the loader because it
describes MeshArrayHandles, and because the preflight's error messages
must name the array the USER can go look at, not our camelCase slot.
The zarr array name behind each handle slot.
Not always the slot name: the CSR label arrays are
label_offsets/label_byteson disk. Lives here rather than in the loader because it describes MeshArrayHandles, and because the preflight's error messages must name the array the USER can go look at, not our camelCase slot.