16 CFR 501.1 - Camera film.
Camera film packaged and labeled for retail sale is exempt from the net quantity statement requirements of part 500 of this chapter which specify how measurement of commodities should be expressed, provided:
(a) The net quantity of contents on packages of movie film and bulk still film is expressed in terms of the number of lineal feet of usable film contained therein.
(b) The net quantity of contents on packages of still film is expressed in terms of the number of exposures the contents will provide. The length and width measurements of the individual exposures, expressed in millimeters or inches, are authorized as an optional statement. (Example: “36 exposures, 36 × 24 mm. or 12 exposures, 2 1/4 × 2 1/4 inches”.)