ASPN FAQs

General FAQs

  • The concept of ASPN originated out of a program titled All Source Position and Navigation, but it has since evolved and is no longer an acronym or an abbreviation. ASPN is just ASPN.

  • ASPN-C is a C-language representation of ASPN and is the canonical reference implementation. One way to ensure your implementation is ASPN-compliant is by verifying it can be converted to and from ASPN-C.

  • Starting July 2026, the ISTO PNT Standards Consortium is intended to maintain, develop, and improve ASPN and other open PNT standards.

  • Starting July 2026, the PNT Standards Consortium is intended to manage all changes in ASPN. Reach out to info@aspn.us for more information on how you can participate in this working group.

Technical FAQs

  • Yes, your implementation can make different decisions and still be ASPN-compliant as long as it can be converted to a compliant representation (such as ASPN-C). Different systems often make different decisions such as units of measurement and coordinate frames, but you are still able to use ASPN.

  • ASPN 2023 uses .yaml to define the data model, because they are both machine-readable and human-readable. The .yamls themselves are not the data model end product; rather, they are converted into the end user's desired product. After the .yamls are put through a conversion tool, example end products include:

    • Documentation (.pdf, .html)

    • Cameo (.xsd)

    • C/C++ headers

    • Various transport IDLs

    As such, describing breaking changes is a function of the end product rather than the .yaml. The summary is:

    • "What is a breaking change?" is an ill-posed question for the ASPN 2023 data model, and

    • When asking "What is a breaking change?" for a specific ASPN 2023 implementation, the answer is, "it depends on how that implementation is generated from the ASPN 2023 data model."

    For additional information, see the documentation on extensibility rules.

  • Yes, modifications made in experimental branches are unregulated by ASPN. Requiring experimental messages to follow ASPN 2023 may prevent a user from experimenting with something that violates, yet improves, ASPN 2023.

    If experimental messages that do not follow ASPN 2023 break your workflow, please choose to ignore those messages. You may safely ignore all experimental messages and branches.

    While the data model modifications are not regulated, there is administrative guidance here to keep the community aligned on how to use experimental branches.