The Flight Dynamics and Control Toolbox

Applied software licenses

Throughout its history, the Flight Dynamics and Control Toolbox has been made available under several software licenses. The basic idea has always been to share the software with the public, while maintaining some degree of control with respect to attribution and distribution terms. The changes reflect changing viewpoints throughout the years; the trend being a move towards the application of generally accepted Open Source and Open Documentation licenses. Copies of all applied licenses have been included at the end of this document.

The first version of the toolbox was published 'in the public domain', meaning no specific licensing terms were defined. To regain some degree of control, FDC versions 1.1, 1.2, 1.3, 1.3 SR1, and 1.3 SR2 were distributed under a custom software license that was loosely based on the license used by emTEX, a LATEX distribution for DOS. It allowed free copying, distribution, and modification of the software, but it restricted commercial use, and the choice of filenames for derivative works.

FDC 1.2.1, FDC 1.3.3, and DUBSI 1.0 used the 'Dutchroll Open Source Software License' (DOSSL), a license that was drafted with the Open Source Definition by the Open Source Initiative in mind. It was based on the 'copyleft' principles of the General Public License and the legal text of Apple's Common Documentation License, and it aimed to provide some protection for webservices too (although not necessary for the toolbox itself).

Shortly thereafter, the Open Software License (OSL) was approved by the OSI board. This license was so close in spirit with the DOSSL that I decided to drop the DOSSL for future work and use the more generally accepted OSL from now on. This license has been used for DUBSI versions 1.0.1 and later, and FDC 1.4 beta.

In order to prevent problems for users who want to combine old versions of the software with newer releases, permission is hereby granted to upgrade any old software license written by M.O. Rauw to the latest version of the Open Software License.

Applied documentation licenses

The documentation that is currently being offered at this website is governed by Apple's Common Documentation License (CDL), a very liberal license that allows free use and distribution of the documents and derivative works, as long as the author is properly referenced and the same license is used for the distribution of derivative works.

Currently, the documentation is only available in PDF or PostScript format, which implies that editing of the existing works is not trivial. In the future, the source codes may be distributed too, be it under the CDL, or one of the Creative Commons licenses.


Below, all the licenses which have been applied for the FDC toolbox and related software and documentation have been listed. Click on the links to see the complete licenses. Notice that these licenses have also been included in the software and literature downloads.

Software or document: License:
'FDC 1.0' Public domain software
'FDC 1.1', 1.2, 1.3, 1.3 SR1, and 1.3 SR2 Custom license for non-commercial use (1)
FDC 1.2.1, FDC 1.3.3, and DUBSI 1.0 Dutchroll Open Source Software License (2)
DUBSI 1.0.1 and 1.0.2, FDC 1.4 beta, and future software packages Open Software License (3)
Documentation (except this website) Apple's Common Documentation License
Template of this website Creative Commons License (attribution, non-commercial, share-alike)

(1) This license is quite restrictive, not very well drafted, and totally obsolete. It is therefore recommended to upgrade older FDC releases to an FDC version that is distributed under either the DOSSL or (even better) the OSL.

(2) The DOSSL is based on existing licenses, so it provides a better foundation than the old restrictive FDC license. Still, this license will not be used for future versions of the FDC toolbox, because the OSL is considered a better alternative.

(3) There have been several revisions of the OSL. This website currently shows version 2.1 of this license. Re-licensing the software from this website under this, or any other version of the OSL is allowed.