What are Film Stocks and how do they differ from a "Film" in Cassette Nest?
Film Stocks are a grouping of the same Film in different formats (35mm, 120, etc.).
Films are instances of a stock in a particular format.
A roll is what you add to your inventory, load in your camera, or view in your logbook.
Films were originally the only way we tracked what we now call Film Stocks. Read more about this change.