The Free Software Foundation (FSF), as the author of the GPL and LGPL licenses, maintains that any software running in the same process space qualifies as "linked" under the terms of these licenses. This includes dynamic and static linking, plug-ins, loadable modules, and, in some cases, even interpreted code.

However, some developers who use GPL licenses interpret these requirements differently and permit certain uses that the FSF does not. A notable example is the Linux kernel, which allows proprietary kernel modules under specific conditions.

For proprietary software authors, the best-case scenario is having to convince a court that the license they accepted, by redistributing GPL-licensed software, permits linking without the obligation to disclose their own source code, as otherwise required by the license.