PRIVATE_HEADER
Specify private header files in a FRAMEWORK shared library target.
Shared library targets marked with the FRAMEWORK property generate frameworks on OS X, iOS and normal shared libraries on other platforms. This property may be set to a list of header files to be placed in the PrivateHeaders directory inside the framework folder. On non-Apple platforms these headers may be installed using the PRIVATE_HEADER option to the install(TARGETS) command.
© 2000–2019 Kitware, Inc. and Contributors
Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.5/prop_tgt/PRIVATE_HEADER.html