Some lenses have distance/ hyperfocal markings - is that with reference to the flange (outer mount point of the lens where it meets the camera body) or the film/sensor plane?
There are two similar, but distinct, concepts to consider:
Focus distance is the distance from the subject to the sensor plane mark on the camera body, which of course corresponds to the location of the sensor/film plane. A lens's minimum focus distance is usually specified, and is always with respect to the sensor/film plane mark. The distances markings or scales on lenses are this type of focus distance, measured from the focal plane marker.
Working distance is the distance between the front of the lens and the subject. Working distance is sometimes specified by lens manufacturers, and often reported by lens reviewers experimentally.
Focal length is a measurement, lens to focuses image when the object being images is at an infinite distance. The light rays from such a distant object, like a star, arrive at the lens as parallel rays. If the lens is a simple convex - convex lens, this measurement is made from the center of the lens to the focal plane.
Modern camera lenses are not simple, they are arrays of lenses. Some are cemented to its neighbor, some are air-spaces, some have positive power (converging) some have negative power. On an optical bench we find two cardinal measuring points. Focal length is measured from the rear nodal. Object distance is measured from the front nodal.
These two cardinal points are generally not listed in the specifications. The position of both can be discovered on an optical bench. These points are often inverted. A telephoto lens features the rear nodal making the barrel shorter thus the lens is less award. A wide-angle often shifts the rear nodal to allow a longer back-focus. This provides room for the mirror and other devices.
If you can achieve magnification 1 (unity or life-size) the focal plane is approximately 2X the focal length behind the rear nodal. The object distance is approximately 2x the focal length forward of the front nodal.