Manufacture date of film vs expiry date

[typicalaussiebloke]

G'day all. Not sure which forum on APUG to post this question but seeing it relates to old colour film I thought it post here.

I have been shooting various Kodak films of the 40s, 50s and 60s, I've recently been looking at the instruction leaflets of each film and I've notice below in small print the month and year of the leaflet which varies from about 1 to 2.5 years prior to film's expiry date on the back of the packet. I would like to know is that date of manufacture of the film itself? If it is then why is the manufacture date vs expire date so inconsistent and varied? I've compared two 60s Kodacolor X films and two 40s Kodacolor films, and in both cases one is manufactured barely over a year prior to expiry date and the other around 2 to 2.5 years prior to expiry date. Can anyone shed light on this?

 

[AgX]

I assume the date on the sheets just to be the date of last editing.
Or of printing.

 

[Oren Grad]

The version date for the instruction leaflet doesn't tell you anything about the manufacturing date for the film.