# 49 73 5A 21 — File format magic numbers

For 49 73 5A 21, offset is 49; extension is isz; format is Compressed ISO image, recorded from its source on 2026-08-03.

- **Hex signature:** 49 73 5A 21
- **Offset:** 49
- **Extension:** isz
- **Format:** Compressed ISO image _(unconfirmed — we could not tie this to the quote below)_

## What the source says

> indows Virtual PC Windows 8 Virtual Hard Disk file format | 49 73 5A 21 | IsZ! | 0 | isz | Compressed <https://en.wikipedia.org/wiki/ISO_image> ISO image | 44 41 41 | DAA | 0 | daa | <https://en.wikipedia.org/wiki/Direct_Access_Archive> Direct Access Archive PowerISO | 4C 66 4C 65 | LfLe | 0 | evt | Windows <https://en.wikipedia.org/wiki/Event_Viewer> Event

## Source

- https://en.wikipedia.org/wiki/List_of_file_signatures

Last verified: 2026-08-03. Review by: 2027-08-03.
Part of [File format magic numbers](https://referencesource.org/file-format-signatures/).