Glossary
Raw (dd) image
A bit-for-bit copy of a disk with no header and no metadata, just the sectors in order. The lowest common denominator of disk imaging.
A raw image, often called a dd image after the Unix tool that makes them, is the disk's sectors written back to back with nothing wrapped around them. No header, no compression, no embedded hash. Offset zero in the file is sector zero of the media, so reading is trivial: multiply the sector number by the sector size and seek.
That simplicity is the point. Everything reads a raw image, which is why
flattening an awkward container to dd is the standard escape hatch when a tool
chokes on E01 or a sparse VMDK. The cost is size (no compression) and that
integrity lives in a separate sidecar hash, not in the file itself.
Split raw sets (.001, .002) are the same data cut into pieces; concatenated
back, they are one image. The parser joins and reads them in the
browser.