This section describes the policy governing the distribution of the CGNS standard and software to the engineering and scientific community at large. By definition, the CGNS standard refers to the Standard Interface Data Structures (SIDS) definitions, the SIDS File Mapping, and the CGNS Mid-Level Library structure (API), as well as all documentation. The CGNS software refers to the CGNS Library source code, the CGIO core routines, and the ADF and HDF5 database manager implementations. The CGNS software may also include sample programs demonstrating the application and use of the CGNS and ADF libraries, as well as some utility programs to assist with the implementation and analysis of CGNS-based files and systems.
Implementation and maintenance of the CGNS distribution policy is the responsibility of the CGNS Steering Committee. The distribution policy dictates that both the CGNS standard and the CGNS software are publicly available, and that the standard and software itself are free of charge. The CGNS software may be used for any purpose, including commercial applications, and may be altered and redistributed, subject to the restrictions described in the CGNS License.
It is the responsibility of the CGNS Steering Committee to enable distribution mechanisms that comply with the following principles:
CGNS is a standard that has been developed with the key concepts of flexibility and extendibility in mind. The standard can accommodate the majority of CFD data quantities in practical usage today; however, some additional capabilities are still being implemented. It is also understood that in the future other additional capabilities will need to be implemented as well. For these reasons, a process for adding to or modifying the existing CGNS standard is necessary.
To address a particular need or deficiency in CGNS, a proposal for a potential change to the standard first must be made. A Technical Team will prepare all proposals. A Technical Team may voluntarily submit the proposal, or a Technical Team may be specifically appointed by the Steering Committee to author the proposal.
A primary requirement of all proposals for modifications will be to support and maintain code compatibility. No additions or changes to the CGNS standard will be adopted which invalidate existing software or data.
Prior to adoption, the Technical Team must present all proposals in an open and public forum. Included with the proposal, a draft of the necessary changes to the SIDS and File Mapping must be provided by the team introducing the modifications. The open forum will then review the proposal, identify any possible shortcomings, and suggest alternatives or improvements.
After the proposal has been presented and deliberated upon, only the Steering Committee has final authority of approval and may elect to do one of three things. First, the Steering Committee may vote by consensus (or a two-thirds majority if necessary) to accept the proposal as is, and thus the changes are approved for implementation. If such approval does not occur, the Steering Committee may still feel there is merit to the proposal, and may choose to defer acceptance of the proposal under the provision that specific changes be made. Finally, the Steering Committee may deem there is little merit in the proposed changes to CGNS, and reserves the right to reject the proposal outright. Whatever the disposition of the proposal, individual organizations may implement UserDefined functions, provided that they adhere to the conventions and standards as defined in the SIDS.