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License Awareness


Highly Reusable Software

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Reporting license incompatibilities


LIDESC reports conflicts by comparing symbol lists for characteristics and incompatibilties. LIDESC does not parse the license text for meaning. Instead a human reads the license text and creates the symbol lists.

Detecting Incompatible Licensing

All modern software development is based on combining separate copyrightable works into a whole. It is possible to create a derivative work by combining software under totally different licenses.

When you create such a combined work, under copyright law you must continue to satisfy all of the terms of all applicable licenses. If there are mutually exclusive license terms, it is not possible to distribute such a work, even though there is no technical obstacle to creating it!

LIDESC was created specifically to detect and report licensing incompatibilities automatically. This tool enables professional software developers to easily work with software having a multitude of licenses. It is not a license enforcement system. But when used properly the command line utility will report when a combined work has incompatible licenses. (See Reporting when incompatible licenses are used)

Reporting GPL incompatibilities

The multi-purpose form provides a demonstration of this capability by reporting incompatibilities with one popular license: the GPL. Other incompatibility checking is possible with additional description files. See Extending LIDESC for an overview.

The GNU General Public License (GPL) is a software license which establishes and preserves all the freedoms the FSF lists as essential and important. The GPL has many uses outside the software published by the GNU project and by most measures, the GPL is the most popular free software license.

Provisions in the GPL put conditions and restrictions on the licensing and distribution of derivative works. A license is termed "GPL-compatible" if there are no mutually exclusive conditions of distributing combined derivative works. The FSF publishes an evaluation of licenses with respect to GPL compatibility, and these were used to create a list of incompatible symbols.

CAUTION: license compatibility reports are only as good as the description files created by human interpretation of license texts. You should obtain them from trusted suppliers, and be careful when creating them yourself. If a symbol list for a license is empty or incomplete, it is not possible to accurately report incompatibility.

WARNING: A simple program like this does nothing more than find and report some of the biggest problems, while leaving others undetected. This system does not match the educated human intelligence required to interpret all the details of licenses. On the other hand, it can be useful to identify some license clauses which deserve extra scrutiny.

To check GPL-compatibility:
  1. Load the form
  2. Based on your interpretation of a license, select the checkboxes for the symbols.
  3. SUBMIT.

This will create a detailed report for that symbol, which includes notes of the section or numbered point in conflict with the GNU General Public License.

  • LIDESC can be extended with new symbolic tags or other description files for other established definitions or local policies as described at Extending LIDESC

    Up to: LIDESC User Documentation

    Librock LIDESC. Software License Analyzer and Compatibility Reporter
    Copyright 2001-2002, Forrest J. Cavalier III, Mib Software
    You may reproduce verbatim copies of this page, but changing it is not allowed.
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