Minimum Focusing Distance?

Is there a standard definition of "minimum focusing distance"? I would expect it to be the distance from the lens to the subject. But it could also be the distance from the subject to the film plane or sensor, although I would expect this to vary because of the differences in camera bodies.

Do different manufacturers use different definitions? e.g. Nikon and Sigma

Minumum focusing distance is measured from the film/sensor plan to a vertical plane that has maximum sharpness and is closest to the film/sensor plane. It is a good idea to test this for yourself, because distance scales marked on lenses or published minimum distances may not be accurate.

Minimum focus distance depends upon focal length of the lens and construction of the lens.

I don't know if Nikon, et al measure minimum focusing distance using differing criteria.

-PB

Preston B. is correct. Many cameras have a mark (a circle with a horizontal line through it) to indicate the location of the focal plane, from where the measurment is made. Focussing distance from the front of the lens is called "working distance".