 This allowed communication may or may not include reusing libraries or routines via dynamic linking — some commentators say it does, the FSF asserts it does not and explicitly adds an exception allowing it in the license for the GNU Classpath re-implementation of the Java library.The interoperability clauses are often pragmatically inoperative due to the vigorous enforcement and strict interpretation of the GPL as it related to integration, aggregation, and linking.It is argued that most forms of incorporation, aggregation, or connectivity with GPL-licensed code is a derivative work that must be licensed under the GPL.