We believe in the power of open source to foster innovation and community-driven 
development and also recognize the need for a sustainable business model and a model
that can handle export-controlled aerospace content. 

For these reasons, Epicycle is offered under a tri-licensing model. The license allows
users to choose between the following three options:

1) LGPL V3.0
2) Evaluation and Education use Only
3) Commercial License

To protect both contributors and our company, we use the Linux Kernel's Developer's 
Certificate of Origin (DCO) as detailed in CONTRIBUTING.txt.

# ========= LGPL v3 Key Principles

1) You must provide the full source code of the LGPL libraries. 

Any application or device using this software under LGPLv3 must provide the complete 
corresponding source code for the LGPL-covered libraries it uses, including any 
modifications. This can be done either by bundling the source or by including a 
written offer with instructions for obtaining it. This obligation applies even if 
the libraries were not modified.

2) Dynamic linking keeps your code proprietary. 

Your application code may remain proprietary if it is a "work that uses the library" 
— typically achieved through dynamic linking. If you statically link to the LGPL 
library, your application may be considered a derivative work and thus subject to 
LGPL licensing terms, including potential open-sourcing. 

3) Users must be able to modify and re-link the library.

Under LGPLv3, users must be given the freedom to replace or modify the LGPL-covered 
libraries. You must also provide the necessary installation information (e.g., scripts, 
interfaces, keys) to allow the modified library to run on the target system. Devices 
that prevent this — such as those using cryptographic lock-downs — are not permitted 
under LGPLv3 (also known as anti-Tivoization requirements).

4) Full compliance is mandatory

If your use case — whether software or hardware — cannot fully comply with all 
LGPLv3 conditions (for example, due to DRM, patents, or platform restrictions), 
then distribution under LGPLv3 is not permitted. In such cases, a commercial 
license may be more appropriate.

# =========  LGPL V3 Software Usage Agreement

GNU LESSER GENERAL PUBLIC LICENSE
Version 3, 29 June 2007

Copyright © 2007 Free Software Foundation, Inc. <https://fsf.org/>

Everyone is permitted to copy and distribute verbatim copies of this license document, 
but changing it is not allowed.

This version of the GNU Lesser General Public License incorporates the terms and 
conditions of version 3 of the GNU General Public License, supplemented by the 
additional permissions listed below.

0. Additional Definitions.
As used herein, “this License” refers to version 3 of the GNU Lesser General Public 
License, and the “GNU GPL” refers to version 3 of the GNU General Public License.

“The Library” refers to a covered work governed by this License, other than an 
Application or a Combined Work as defined below.

An “Application” is any work that makes use of an interface provided by the Library, 
but which is not otherwise based on the Library. Defining a subclass of a class 
defined by the Library is deemed a mode of using an interface provided by the Library.

A “Combined Work” is a work produced by combining or linking an Application with the
Library. The particular version of the Library with which the Combined Work was made
is also called the “Linked Version”.

The “Minimal Corresponding Source” for a Combined Work means the Corresponding Source
for the Combined Work, excluding any source code for portions of the Combined Work
that, considered in isolation, are based on the Application, and not on the 
Linked Version.

The “Corresponding Application Code” for a Combined Work means the object code and/or
source code for the Application, including any data and utility programs needed for
reproducing the Combined Work from the Application, but excluding the System 
Libraries of the Combined Work.

1. Exception to Section 3 of the GNU GPL.
You may convey a covered work under sections 3 and 4 of this License without being
bound by section 3 of the GNU GPL.

2. Conveying Modified Versions.
If you modify a copy of the Library, and, in your modifications, a facility refers
to a function or data to be supplied by an Application that uses the facility
(other than as an argument passed when the facility is invoked), then you may convey
a copy of the modified version:

a) under this License, provided that you make a good faith effort to ensure that,
in the event an Application does not supply the function or data, the facility still
operates, and performs whatever part of its purpose remains meaningful, or
b) under the GNU GPL, with none of the additional permissions of this License 
applicable to that copy.
3. Object Code Incorporating Material from Library Header Files.
The object code form of an Application may incorporate material from a header file
that is part of the Library. You may convey such object code under terms of your 
choice, provided that, if the incorporated material is not limited to numerical 
parameters, data structure layouts and accessors, or small macros, inline functions
and templates (ten or fewer lines in length), you do both of the following:

a) Give prominent notice with each copy of the object code that the Library is used
in it and that the Library and its use are covered by this License.
b) Accompany the object code with a copy of the GNU GPL and this license document.
4. Combined Works.
You may convey a Combined Work under terms of your choice that, taken together, 
effectively do not restrict modification of the portions of the Library contained in
the Combined Work and reverse engineering for debugging such modifications, if
you also do each of the following:

a) Give prominent notice with each copy of the Combined Work that the Library is 
used in it and that the Library and its use are covered by this License.
b) Accompany the Combined Work with a copy of the GNU GPL and this license document.
c) For a Combined Work that displays copyright notices during execution, include 
the copyright notice for the Library among these notices, as well as a reference 
directing the user to the copies of the GNU GPL and this license document.
d) Do one of the following:
0) Convey the Minimal Corresponding Source under the terms of this License, and the 
Corresponding Application Code in a form suitable for, and under terms that permit, 
the user to recombine or relink the Application with a modified version of the Linked 
Version to produce a modified Combined Work, in the manner specified by section 6 of 
the GNU GPL for conveying Corresponding Source.
1) Use a suitable shared library mechanism for linking with the Library. A suitable 
mechanism is one that (a) uses at run time a copy of the Library already present on 
the user's computer system, and (b) will operate properly with a modified version of 
the Library that is interface-compatible with the Linked Version.
e) Provide Installation Information, but only if you would otherwise be required to 
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such information is necessary to install and execute a modified version of the Combined 
Work produced by recombining or relinking the Application with a modified version of 
the Linked Version. (If you use option 4d0, the Installation Information must accompany 
the Minimal Corresponding Source and Corresponding Application Code. If you use option 
4d1, you must provide the Installation Information in the manner specified by section 
6 of the GNU GPL for conveying Corresponding Source.)
5. Combined Libraries.
You may place library facilities that are a work based on the Library side by side 
in a single library together with other library facilities that are not Applications 
and are not covered by this License, and convey such a combined library under terms 
of your choice, if you do both of the following:

a) Accompany the combined library with a copy of the same work based on the Library, 
uncombined with any other library facilities, conveyed under the terms of this License.
b) Give prominent notice with the combined library that part of it is a work based on 
the Library, and explaining where to find the accompanying uncombined form of the same work.
6. Revised Versions of the GNU Lesser General Public License.
The Free Software Foundation may publish revised and/or new versions of the GNU Lesser 
General Public License from time to time. Such new versions will be similar in spirit 
to the present version, but may differ in detail to address new problems or concerns.

Each version is given a distinguishing version number. If the Library as you received 
it specifies that a certain numbered version of the GNU Lesser General Public License 
“or any later version” applies to it, you have the option of following the terms and 
conditions either of that published version or of any later version published by the 
Free Software Foundation. If the Library as you received it does not specify a version 
number of the GNU Lesser General Public License, you may choose any version of the GNU 
Lesser General Public License ever published by the Free Software Foundation.

If the Library as you received it specifies that a proxy can decide whether future 
versions of the GNU Lesser General Public License shall apply, that proxy's public 
statement of acceptance of any version is permanent authorization for you to choose 
that version for the Library.

# ========= Evaluation and Educational License

Gen Astro Evaluation and Educational License

Copyright 2025 Gen Astro LLC

This work is licensed for evaluation and educational purposes only. It may NOT be 
used for formal development, integration and testing, operations or any other 
commercial purpose without the purchase of a commercial license from Gen Astro LLC.

The above copyright notice and this permission notice shall be included in all 
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

# ========= Gen Astro Commercial Licenses

The commercial license is a signed contractual agreement that allows you to 
use our software without being subject to the requirements of the LGPL v3.0 or
other open-source licenses.

Key features of the commercial license include:

Project-Based Licensing: Commercial licenses are typically issued per project, 
with flexible terms that support unlimited users and installations as needed 
within that project.

Keep Your Code Proprietary: Any software, modules, or plugins that you develop 
under the commercial license may be kept fully proprietary — there is no 
obligation to release source code or contribute back.

Flexible License Types.  We offer:

- Annual subscription licenses
- Perpetual licenses (one-time payment, non-expiring)
- Site-wide licenses for organizational use
- Framework licenses for government or large-scale multi-mission systems
- Access to Enhanced Capabilities
- Commercial licensees receive full access to our Enterprise features, including
  advanced modules and capabilities not available under the open-source license
  (export control laws apply)