Technical Team/Proposals/2010-10-21/Composite licensing

Status

Draft

Issue

There are some licensing scenarios which are not expressable in SPDX. For example, there is currently no way to express that a file can be used under the licenses A and B or A and C.

Use cases

The set of use cases we need to be able to describe in SPDX is:

1. a single license
2. choice of one from multiple single licenses
3. multiple licenses (conjunctive)
4. choice of one from multiple conjunctive license sets

Proposal

Introduce a license set concept to cover all these use cases. Specifically, a `ConjunctiveLicenseSet` and a `DisjunctiveLicenseSet`. Members of these types of sets would be of type `License`, `ConjunctiveLicenseSet` or `DisjunctiveLicenseSet`. This would allow composing licensing information in arbitrary conjunctive and disjunctive groupings.

The definition of `License` would not change. The `DeclaredLicense` and `DetectedLicense` properties would be updated to allow their value to be a `License`, `ConjunctiveLicenseSet`, or `DisjunctiveLicenseSet`.

Examples

Single license

<code><br />    <Package><br />      <DeclaredLicense><br />        <rdf:Description rdf:about="license:GPL" /><br />      </DeclaredLicense><br />    </Package><br /></code>

Disjunctive licenses

<code><br />    <Package><br />      <DeclaredLicense><br />        <ConjunctiveLicenseSet><br />          <licenses rdf:parseType="Collection"><br />            <rdf:Description rdf:about="license:GPL" /><br />            <rdf:Description rdf:about="license:BSD" /><br />          </licenses><br />        </ConjunctiveLicenseSet><br />      </DeclaredLicense><br />    </Package><br /></code>

Complex disjunctive licenses

<code><br />    <Package><br />      <DeclaredLicense><br />        <DisjuntiveLicenseSet><br />          <licenses rdf:parseType="Collection"><br />            <ConjunctiveLicenseSet><br />              <licenses rdf:parseType="Collection"><br />                <rdf:Description rdf:about="license:GPL" /><br />                <rdf:Description rdf:about="license:BSD" /><br />              </licenses><br />            </ConjunctiveLicenseSet><br />            <ConjunctiveLicenseSet><br />              <licenses rdf:parseType="Collection"><br />                <rdf:Description rdf:about="license:GPL" /><br />                <rdf:Description rdf:about="license:Apache" /><br />              </licenses><br />            </ConjunctiveLicenseSet><br />          </licenses><br />        </DisjuntiveLicenseSet><br />      </DeclaredLicense><br />    </Package><br /><br /></code>