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

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

Disjunctive licenses

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

Complex disjunctive licenses

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

Changes

These changes are available in the 'composite-licensing' branch of https://github.com/pezra/spdx-spec.git. A full version of the spec with these changes is attached, as is a patch file to implement these changes.