In the ISO standard for light meter calibration, there is the K factor for reflected light meters and the C factor for incident light meters. K is the reflected-light meter calibration constant

From Wikipedia...
"Calibration constantsDetermination of calibration constants has been largely subjective; ISO 2720:1974 states that

"The constants K and C shall be chosen by statistical analysis of the results of a large number of tests carried out to determine the acceptability to a large number of observers, of a number of photographs, for which the exposure was known, obtained under various conditions of subject manner and over a range of luminances.

"In practice, the variation of the calibration constants among manufacturers is considerably less than this statement might imply, and values have changed little since the early 1970s.

"ISO 2720:1974 recommends a range for K of 10.6 to 13.4 with luminance in cd/mē. Two values for K are in common use: 12.5 (Canon, Nikon, and Sekonic[1]) and 14 (Kenko[2] and Pentax); the difference between the two values is approximately 1/6 EV."

Not sure why the K values are an order of magnitude different between what you mentioned vs. the K factor in the ISO standard, but since yours expressed no units, that might be the source of the discrepancy.