In article <4cnfq5$d2b@cello.hpl.hp.com>, jacobson@cello.hpl.hp.com says...

>At some time or other there was a re-defintion of the ASA film speed
>that changed some film speeds a bit, so that may account for this. But
>I know absolutely for sure that the Kodachome I used in the 1950s was
>ASA 10.

Yes, followed by the beautiful Kodachrome II (25) and the icky (except on very grey days...) Kodachrome X (64). Then came K25, K64, and, uh
finally (?), K200 (the only Kodachrome I still use - the K64 contrast
and blah greens, and the K25 tendency toward greenish slides and muted color [occasionally nice, still] finally got to me, and I switched).
Hope This Helps