Compatibility of a particular first (leading) license with another (subordinate) license becomes an issue when a work that is licensed under the other license is to be integrated into a common work and to be compliantly copied and distributed under the leading license.
Such compatibility is assumed, if
- compatibility with the other license is explicitly ruled in a particular license, or
- the two licenses in question both do not contain a copyleft clause, or
- the leading license contains a copyleft clause and the other license does not and also does not impose any obligation that the first license does not allow to impose.

Incompatibility is assumed, if
- incompatibility with another license is explicitly ruled in a particular license, or
- one license imposes an obligation that the other license does not allow to impose, or
- the two licenses in question both contain a copyleft clause and no license contains an explicit compatibility clause for this license combination.

In addition, the term "dependent compatibility" has been introduced. Such compatibility is assumed if the two licenses are incompatible, but one or both licenses explicitly allow the license to be updated to a newer version or to switch to another license that is then no longer incompatible. The respective change path is described in the "Interpretation" of the DEPENDING COMPATIBILITY line of the checklist.