Specify output directory for Fortran modules provided by the target.
If the target contains Fortran source files that provide modules and the compiler supports a module output directory this specifies the directory in which the modules will be placed. When this property is not set the modules will be placed in the build directory corresponding to the target's source directory. If the variable CMAKE_Fortran_MODULE_DIRECTORY is set when a target is created its value is used to initialize this property.
Note that some compilers will automatically search the module output directory for modules USEd during compilation but others will not. If your sources USE modules their location must be specified by INCLUDE_DIRECTORIES regardless of this property.