Brian Atherton
Well-known
...Don't know what to tell you about how to tell exposed/unexposed rolls apart if you leave the leader out - I've never understood why people do that.
Bend the film leader over a couple of times to crease it or write an ‘X’ on the leader with a marker pen. Some leave the leader out after exposing a film because they find it easier to just pull the film out of the cassette when loading film in the dark into developing reels, rather than prising off the cassette cap.