Default Compression (with preset dictionary) — file signature 78 BB at offset 0

For Default Compression (with preset dictionary), hex signature is 78 BB; offset is 0; extension is zlib, verified against its source on 2026-09-22.

What the source says

78 01 | x␁ | 0 | zlib | No Compression (no preset dictionary) | 78 5E | x^ | Best speed (no preset dictionary) | 78 9C | xœ | Default Compression (no preset dictionary) | 78 DA | xÚ | Best Compression (no preset dictionary) | 78 20 | x␠ | No Compression (with preset dictionary) | 78 7D | x} | Best speed (with preset dictionary) | 78 BB | x» | Default Compression (with preset dictionary) |

— en.wikipedia.org, retrieved 2026-09-22

Source

• en.wikipedia.orghttps://en.wikipedia.org/wiki/List_of_file_signatures

Last verified against source: 2026-09-22. Due for re-check by 2027-09-22. This page as Markdown · OKF bundle · full dataset as JSON.