What does "//VTK::Light::Impl" mean?

Support
4

Let me see if I did this correctly, would the replacement tag for //VTK::Light::Dec be and this would be considered all the code in VTK::Light::Impl?

https://gitlab.kitware.com/vtk/vtk/-/blob/66096615a1b90be9f401bfefea77ceb4e2189fae/Rendering/OpenGL2/vtkOpenGLPolyDataMapper.cxx#L1104-1465 ?