Embodiments include a method, a manual device, a handheld manual device, a handheld writing device, a system, and an apparatus. An embodiment provides a system. The system includes a manual device that includes a writing element operable to discharge a marking substance on a surface in response to a movement of the writing element upon the surface. The system also includes a sensor operable to acquire information corresponding to an environment of the manual device. The system further includes a verification module operable to determine a correspondence between a first aspect of the environment of the manual device and a second aspect of the environment of the manual device.