I think you are getting confused with the DIN number. The number following the ISO 400/nn is the DIN number which is a number that represents the speed of the film in the same was as the ISO number except that it is a log scale.(posted 8860 days ago)ISO 100 = DIN 21 ISO 200 = DIN 24 ISO 400 = DIN 27 ISO 800 = DIN 30 ISO 1600 = DIN 33 ISO 3200 = DIN 36
The DIN numbers increase 3 for every factor of two in ISO.
This number has nothing to do with the "temperature of the film."
They put these numbers on because some light meters are calibrated in the DIN numbers. It makes it easier to compute because adding or subtracting a stop is just simple addition .. the beauty of logrighms.
I am not sure about the too cold question. I suspect that 38F is fine as long as the film has not been opened, and that you take the proper amount of time to let it come to room temperature before opening it.
Somebody else might know wheather or not 38F is too cold or not.
Ken