CMAKE__POSTFIX

From Get docs
Cmake/docs/3.21/variable/cmake config postfix


CMAKE__POSTFIX

Default filename postfix for libraries under configuration <CONFIG>.

When a non-executable target is created its _POSTFIX target property is initialized with the value of this variable if it is set.

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https://cmake.org/cmake/help/v3.21/variable/CMAKE_CONFIG_POSTFIX.html