The OSL has a termination clause intended to dissuade users from filing patent infringement lawsuits:
Warranty of provenance
Another goal of the OSL is to warrant provenance.
Comparison with the LGPL/GPL
The OSL is intended to be similar to the LGPL. Note that the definition of Derivative Works in the OSL does not cover linking to OSL software/libraries so software that merely links to OSL software is not subject to the OSL license. The OSL is not compatible with the GPL. It has been claimed that the OSL is intended to be legally stronger than the GPL, however, unlike the GPL, the OSL has never been tested in court and is not widely used.
Assent to license
The restriction contained in Section 9 of the OSL reads: In its analysis of the OSL the Free Software Foundation claims that "this requirement means that distributing OSL software on ordinary FTP sites, sending patches to ordinary mailing lists, or storing the software in an ordinary version control system, can arguably be a violation of the license and would subject violators to possible termination of the license. Thus, the OSL makes it challenging to develop software using the ordinary tools of Free Software development."
Distribution
If the FSF claim is true then the main difference between the GPL and OSL concerns possible restrictions on redistribution. Both licenses impose a kind of reciprocity condition requiring authors of extensions to the software to license those extensions with the respective license of the original work.
Patent action termination clause
The patent action termination clause, described above, is a further significant difference between the OSL and GPL.
Further provisions
Derivative Works must be distributed under the same license.
Covered works that are distributed must be accompanied by the source code, or access to it made available.
No restrictions on charging money for programs covered by the license, but source code must be included or made available for a reasonable fee.
Covered works that are distributed must include a verbatim copy of the license.
Distribution implies a royalty-free license for any patents embodied in the software.
Later versions
It is optional, though common for the copyright holder to add “or any later version” to the distribution terms in order to allow distribution under future versions of the license. This term is not directly mentioned in the OSL. However, it would seem to violate section 16, which requires a verbatim copy of the license.
