Licensing Explained
This document provides some explanation of how the licensing under which OSE is made available works in practice.
C++ Class Library
The C++ class library component of OSE is made available under the terms and conditions of the Q Public License (QPL) version 1.0. The QPL was originally created by Troll Tech for the Qt C++ class library and qualifies as being an Open Source license under the Open Source model. The licence is free to be used by other Open Source developers to apply to their own work, such as is being done here with its use in conjunction with the C++ class library component of OSE.
So long as you abide by the terms and conditions of the QPL you can use the C++ class library component of OSE without charge.
Of the conditions in the QPL, that which is most important to understand is clause 6.
6. You may develop application programs, reusable components and other software items that link with the original or modified versions of the Software. These items, when distributed, are subject to the following requirements:
a. You must ensure that all recipients of machine-executable forms of these items are also able to receive and use the complete machine-readable source code to the items without any charge beyond the costs of data transfer.
b. You must explicitly license all recipients of your items to use and re-distribute original and modified versions of the items in both machine-executable and source code forms. The recipients must be able to do so without any charges whatsoever, and they must be able to re-distribute to anyone they choose.
c. If the items are not available to the general public, and the initial developer of the Software requests a copy of the items, then you must supply one.
If you are a commercial organisation, this means that you can still develop and sell an application which links with the C++ class library component of OSE, however, you must supply the source code to your application to the customer who buys it from you for no additional charge beyond the cost of media or other means of data transfer used to deliver it to the customer. Further, you cannot prevent that customer from turning around and modifying or redistributing your application, including its source code, to someone else.
Because of the above conditions, the use of this particular Open Source license for the C++ library component of OSE might well be unacceptable, as you are unlikely to agree to giving away the source code to the products you sell. If you want to use the C++ class library component of OSE in a closed source application, you will need to contact Dumpleton Software Consulting and purchase a commercial use license. This alternative license will permit you to use OSE in an application without forcing you to also make available the source code for your application.
Note that there is more to the above conditions and the QPL than covered by the summary above. You should ensure that you properly read the QPL and understand how it applies to your situation before using OSE.
Python Wrappers
The source code for the Python wrappers which encapsulate aspects of the functionality provided by the C++ class library are made available under the terms of a BSD license.
Note that the resultant loadable module created to support the Python wrappers will contain object code resulting from the compilation of source code from the C++ class library. Under normal circumstances this would mean that use of the Python wrappers would also be governed by the terms and conditions of the Q Public License. As a special exception, provided that no changes are made to any of the C++ class library source code, the Python wrappers may be used without the terms and conditions of the Q Public License applying to your Python based application. This exception does not invalidate any other reason why an application making use of the C++ class library might be covered by the terms and conditions of the Q Public License.
Thus, if you are developing C++ applications using the C++ class library component of OSE, you are bound by the Q Public License. That license requires you to make the source code for your application freely available if you distribute it to others as described above. If on the other hand your application is developed completely in Python using only the Python wrappers, the special exception listed above means that you are not obligated to make your Python code freely available. You must however still provide the source code of OSE to any recipient of any application of yours which you distribute which makes use of those Python wrappers.
Build Environment
The build environment known as "makeit" which is supplied as a component of OSE, but which is also available as a separate package in its own right, is made available under the terms and conditions of a BSD license. Software made available under a BSD license can generally be used with no impediments in either Open Source or Closed Source applications. Further, there are no restrictions on you in respect of what changes you may make to software under a BSD license, except to the extent to which copyright notices must be preserved in the original code.