CMP0106

The Documentation module is removed.

The Documentation was added as a support mechanism for the VTK project and was tuned for that project. Instead of CMake providing this module with (now old) VTK patterns for cache variables and required packages, the module is now deprecated by CMake itself.

The OLD behavior of this policy is for Documentation to add cache variables and find VTK documentation dependent packages. The NEW behavior is to act as an empty module.

This policy was introduced in CMake version 3.18. CMake version 3.19.0-rc3 warns when the policy is not set and uses OLD behavior. Use the cmake_policy() command to set it to OLD or NEW explicitly.