Help with cartelle! (Rome)

Hello All,

Any translator around here!? I need help with the calculation of a cartella!
I usually quote and charge per Protected content of the original documents, but a potential Italian client has asked me to quote per cartella. This is a bit tricky because it seems that the concept of cartella and how many 'caratteri spazi inclusi' are included varies according to very mysterious rules...

Any help would be greatly needed! This is for a translation from English in Frenc- but may need the same for translations from Italian into French
Anne