# Main use cases for COMPAT\_VERSION of project() (in new CMake 4.1)
**URL:** https://discourse.cmake.org/t/main-use-cases-for-compat-version-of-project-in-new-cmake-4-1/14289
**Category:** Usage
**Created:** [June 27, 2025, 10:47am UTC](https://discourse.cmake.org/t/main-use-cases-for-compat-version-of-project-in-new-cmake-4-1/14289 "2025-06-27T10:47:07Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@leha-bot](https://discourse.cmake.org/u/leha-bot)
#### Post date: [June 27, 2025, 10:47am UTC](https://discourse.cmake.org/t/main-use-cases-for-compat-version-of-project-in-new-cmake-4-1/14289/1 "2025-06-27T10:47:07Z")
It’s unclear the main usage of this feature and potential use-cases. The most similar things I thought, was [write\_basic\_package\_version\_file](https://cmake.org/cmake/help/latest/module/CMakePackageConfigHelpers.html#command:write_basic_package_version_file) and their COMPATIBILITY ( `AnyNewerVersion`, `SameMinor`, `SameMajor`, `ExactVersion`)
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### Author:  [@vito.gamberini](https://discourse.cmake.org/u/vito.gamberini)
#### Post date: [June 28, 2025, 3:46pm UTC](https://discourse.cmake.org/t/main-use-cases-for-compat-version-of-project-in-new-cmake-4-1/14289/2 "2025-06-28T15:46:19Z")
CPS has a more comprehensive concept of compatibility than the enumerated set of options provided by `write_basic_package_version_file()`, namely here a minimum version back to which the artifact is fully backwards compatible. This might span multiple major versions, but not all.
`COMPAT_VERSION` is explicitly for CPS, it has no bearing on the CMakeConfig system or the mechanisms provided by `-config-version` files that system uses.
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### Author:  [@leha-bot](https://discourse.cmake.org/u/leha-bot)
#### Post date: [June 28, 2025, 4:03pm UTC](https://discourse.cmake.org/t/main-use-cases-for-compat-version-of-project-in-new-cmake-4-1/14289/3 "2025-06-28T16:03:48Z")
oh, thanks, actually forgot about this CPS aspect, time to recheck the spec 🙂