mirror of https://referencesource.org/file-format-signatures/

README.md

@@ -0,0 +1,53 @@
+---
+pretty_name: "File format magic numbers"
+license: other
+license_name: source-terms-cited
+license_link: https://referencesource.org/file-format-signatures/
+language:
+- en
+tags:
+- reference-data
+- provenance
+- referencesource-org
+configs:
+- config_name: default
+  data_files:
+  - split: train
+    path: data/records.jsonl
+---
+# File format magic numbers
+
+**Canonical, always-current version: https://referencesource.org/file-format-signatures/**
+Machine-readable: https://referencesource.org/file-format-signatures/data.json — this mirror is a point-in-time copy.
+
+- **Last verified:** 2026-08-03
+- **Stale after:** 2027-08-03 (past this date, prefer the canonical copy —
+  it re-verifies on a cadence this snapshot does not)
+- **Records:** 229
+
+The leading bytes (magic number / file signature) that identify a file format, with its usual extension. Answers 'what actually is this file' when the extension is wrong or missing.
+
+## Provenance — what every record carries
+
+Every record carries `source` (the URL the value was read from) and
+`source_quote` (a verbatim quote from that page stating it). A value you
+cannot check against its page is indistinguishable from an invented one;
+these can all be checked. Each record is also individually addressable on
+the canonical site at its `url`.
+
+## Licence position
+
+CC BY-SA 4.0 (source: Wikipedia)
+
+Facts are not copyrightable; what this dataset takes from each source is a
+fact plus a short attributed quote linking back to the page that states it.
+
+## Sources
+
+- https://en.wikipedia.org/wiki/List_of_file_signatures
+
+## Fields
+
+See any record in `data/records.jsonl` — field names are self-describing,
+and the canonical page for each record renders them with labels:
+https://referencesource.org/file-format-signatures/