Many Pipeline Parameters contain the parameter /Update_C3d_File=

If this parameter is set to TRUE, Visual3D attempts to update the c3d file stored on disk; the consequence is that you will have overwritten the existing C3D file permanently. If you were editing parameters, this is usually the desired result because you shouldn't need to modify parameters every time the C3D file is opened.

If this parameter is set to FALSE, the C3D parameters are updated in the Workspace (e.g. cmo file), but the C3D file has not been updated on disk.