How Debian DFSG Treats GFDL Documentation

Debian strictly applies the Debian Free Software Guidelines (DFSG) to both source code and documentation, leading to a nuanced treatment of the GNU Free Documentation License (GFDL). While the Free Software Foundation designed the GFDL specifically for technical manuals, Debian considers GFDL-licensed documentation compliant with the DFSG only if it contains no unmodifiable components. Consequently, GFDL materials without Invariant Sections are accepted into Debian's official main distribution, whereas works featuring Invariant Sections are deemed non-free and relegated to the non-free repository.

Application of DFSG to Documentation

The Debian project does not distinguish between executable binaries, source code, and documentation when assessing software freedom. Under the Debian Social Contract, every component included in the core operating system must adhere to the DFSG. This approach contrasts with the views of other open-source organizations that apply more relaxed licensing rules to written manuals and media assets.

The Conflict with GFDL Invariant Sections

The primary conflict between the DFSG and the GFDL stems from the license's provision for "Invariant Sections" and "Cover Texts." The GFDL permits authors to designate certain secondary sections—typically covering the author's philosophical, political, or historical viewpoints—as unalterable.

Debian identifies several explicit conflicts between this mechanism and the DFSG:

  • DFSG 3 (Derived Works): The guidelines mandate that licenses must allow modifications and derived works under the same terms. Invariant sections explicitly forbid modification, preventing downstream users from correcting errors, translating certain sections, or condensing the text.
  • DFSG 4 (Integrity of the Author's Source Code): While the DFSG allows authors to require patch files to protect the integrity of code, it does not permit outright bans on modifying substantial portions of a work.
  • DFSG 6 (No Discrimination Against Fields of Endeavor): Technical and legal restrictions, such as DRM-prohibiting clauses in the GFDL that forbid distributing modified versions on copy-protected media, create legal ambiguities for commercial distribution.

General Resolution 2006-001

To settle years of debate regarding how to handle standard GNU documentation bundled with software like GCC, Emacs, and Coreutils, Debian conducted a project-wide vote in 2006 (General Resolution 2006-001).

The outcome formally established Debian's official policy:

  1. GFDL Without Invariant Sections: Deemed fully DFSG-compliant. If a manual uses the GFDL with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts, it is accepted into the main repository.
  2. GFDL With Invariant Sections: Deemed non-compliant with the DFSG. Works that include unmodifiable sections cannot be part of the official Debian operating system.

Current Implementation in the Debian Archive

Following the 2006 resolution, Debian package maintainers audited software packages containing GFDL documentation. Packages carrying manuals with Invariant Sections had their documentation split into separate packages and relocated to the non-free archive component, while the underlying software remained in main. In some instances where upstream licensing made this split impractical, maintainers chose to excise the documentation entirely from the package to ensure DFSG compliance.