The CGNS community can help you to understand, use and even participate to the CGNS standard. There are various means. As a user of the CGNS files and tools, you can ask questions to the CGNS Discussion Forum or browse the web resources. If you are a developer and you want to install the libs, the docs or the tools you jump to Development support.
The discussion forum is available on GitHub.com. You must have an account. Notifications of new posts are controlled by setting the proper watch notifications for the CGNS/CGNS repository.
Prior to 2020, there was a CGNSTalk mailing list (connected to NASA) that has since been discontinued.
The CGNSTalk mailing list archives [
GZIPPED TXT FILE] are available from 2000 to 2020.
None listed yet.
The CGNS libs and tools are hosted on Github; the associated documentation can be found on this page.
The documentation is generated from text files. We use Sphinx to produce the web pages from these text files and a set of layout templates. The template we use for CGNS is a modified version of the Guzzle template. This modified version is released with the doc sources.
You have to install the production libs and tools, you have to make available:
Sphinx (v3.2+) and all its associated libs (see below)
guzzle sphinx theme
To check your production configuration, open an Unix shell, for example bash and run the commands (do not type the $ sign which is supposed to be the shell prompt:
$ python Python 3.9.1 (default, Feb 8 2021, 12:46:16) [GCC 4.8.5 20150623 (Red Hat 4.8.5-16)] on linux Type "help", "copyright", "credits" or "license" for more information. >>>
If the python version is not 3.x.y or if you do not have python, you have to install it. On some systems, you would have to type python3 to run python instead of only python without version number.
Once python 3.x.y is there, go to STEP 2.
Now your python version is 3.x.y and you have to use the 3.x version in all path we mention in next steps. The example are using 3.7 and you should change these path with your own 3.x to make it work properly.
The >>> sign is the python interpreter prompt. We resume our test by trying to find out if our python installation has all required packages:
>>> import sphinx >>> import guzzle_sphinx_theme
If the command fails on import sphinx, you can install it using the shell command (not a python command):
$ pip install sphinx
If the command fails on the import guzzle_sphinx_theme you have to install the guzzle package. The guzzle theme can be found in the CGNS doc sources, you find the package in <clone-directory>/ You can find below an example installation of guzzle you have to modify to fit your own environment.
mkdir /tmp/gz cp guzzle_sphinx_theme-master.zip /tmp/gz cd /tmp/gz unzip guzzle_sphinx_theme-master.zip cd guzzle_sphinx_theme-master/ python setup.py build mkdir /tmp/gz/install export PYTHONPATH=/tmp/gz/install/lib/python3.7/site-packages/:$PYTHONPATH python setup.py install --prefix=/tmp/gz/install
Once you have installed guzzle, make sure the Python .egg file is uncompressed. For example, on a Unix platform with a sh shell:
cd /tmp/gz/install/lib/python3.7/site-packages unzip guzzle_sphinx_theme-0.7.11-py3.7.egg
If you still have an error in import guzzle_sphinx_theme you can move the page this way:
cd /tmp/gz/install/lib/python3.7/site-packages mv guzzle_sphinx_theme-0.7.11-py3.7.egg/guzzle_sphix_theme .
Try again this STEP 1 if succeed, you jump to STEP 2
Congrats! you are now ready to contribute to the CGNS documentation.
We retrieve the last version from the git repository.
Go to the directory where you want to produce the documentation,
say for example:
cd /my/own/local/doc/directory git clone https://github.com/CGNS/cgns.github.io.git git checkout doc-rest-migration
You need to have git to get the actual documentation source tree. We cannot detail here how to install git or how to allow it to access to the CGNS repository. If you really are lost, please use CGNS mailing list.
Everything is ready now, once you are in
all sources are in:
If this directory is not there, be sure you are on the doc-rest-migration branch.
Most of the files to be created/edited are rst files located in and below CGNS-ReST-site/source/
To produce the documentation, you run:
cd CGNS-ReST-site sh ./build.sh
All doc is generated into:
To check the produced documentation, you open a web browser (chrome,
firefox, whatever…) and you open the top page which is
(in this example we are still in the
Second you run the build.sh script, it generates all the stuff and copies a final/ usable html directory with all required files. You can copy this directory at any place you want, the directory is self-contained.
The equation rendering makes a reference to an external link, so that you may have issues with the equations if you are not connected to the public internet.
Now you open your favorite text editor. You follow the documentation editing recommendations described hereafter and you loop on steps 3 and 4.
You are done with your editing. You commit your changes with a nice comment and you push it to the repository:
git add -A git commit -m 'update section 4.2.1' git push
If some modifications have been applied since you where editing, you have to
perform a merge by yourself after a
Doc Conventions for these CGNS web pages
Top level header ================ Second level ------------ Third level ^^^^^^^^^^^ Fourth level ~~~~~~~~~~~~ Fith level ++++++++++
The index is generated, you just have to mention an index entry in the text. For example, if you wan to add a reference to boundary condition in the index, you add:
:index:`Reference-state` data is useful for situations where :index:`boundary-condition` is not provided, and flow solvers are free to enforce any appropriate boundary condition equations.
You note in this example we also add an index for the reference-state. We have now an entry boundary-condition and an entry reference-state.
We can use a similar to add two entries at the same time. In that case you have an entry boundary-condition in the index at reference-state and vice-versa.
Reference-state data is useful for situations where :index:`index entries <pair: boundary-condition; reference-state>` is not provided, and flow solvers are free to enforce any appropriate boundary condition equations.
An internal link is composed of its anchor (the place in the web site where you want to go to) and a reference (the words wich triggers the jump to the anchor).
An anchor is defined with:
Note the leading underscode and the single colon. The anchor test should be contiguous and we suggest using the camel case syntax.
The actual link is inserted with:
You read this text with your eyes but you can also :ref:`click on to jump elsewhere <ThisIsThePlaceYouWantToJumpTo>`.
The anchor in into angular brackets, the clickable text is user defined.
For an external reference the syntax is:
Info can be found on `other site web page < URL to other site page >`_.
Do not miss the trailing underscore.
To add a quote in the text, inside a box (this is the default style of our template), shift the text block on the right:
Generating documentation from source code is possible. But code does not explain by itself -- C compiler (stdout)
Generating documentation from source code is possible.
But code does not explain by itself
—C compiler (stdout)
Header with 2 cols
A set of special blocks are called admonitions. These includes notes, warnings… their layout, again, is set by the style we use.
.. note:: if you do not read the doc .. warning:: no way you succeed .. tip:: start from first page
if you do not read the doc
no way you succeed
start from first page
There are several ways to insert an image. The first example adds an image as a new paragraph:
.. image:: ../path/to/image/file.png :width: 200px :align: center
The second way is to inline the image so that it appears in the text without creating a new paragraph. You have to declare the image using a label enclosed with vertical bars:
.. |inline_image_label| image:: ../../path/to/image/file.png
Then you refer to thus label in the text where you want the insertion:
When you read this text you have an image like |inline_image_label| without any break.
Preferred image formats are
.gif or even
Image file path is relative to current doc directory and should refer to
images directory where all images are. It is sometimes a bit
difficult to find out which is the level of directory you are into. You
have to go back to the root directory of the doc generation, you add as
../ as you entered directories up to your file.
The root directory is the one where you can see
For example, if you are editing
an image path should have three backwards items,
../../.. which are
Your image in this file has the path:
Inserting footnotes, citation or any reference can be defined in several ways:
In the text you can add references such as _, _, [CIT2002]_. ..  In the footnote. ..  A footnote contains body elements, consistently indented by at least 3 spaces. .. [CIT2002] Just like a footnote, except the label is textual.
Just like a footnote, except the label is textual.
The CPEX process requires multiple docs.
The CPEX should include the following information:
Name(s) and organization(s) of proposer(s)
E-mail contact information
General description of extension
Reason or need for extension
A SIDS detailed description of extension using similar documentation style found in the SIDS
File Mapping description of Node Attributes, following the prescription given in existing Node Description Documentation
Specific example(s) of extension