In the help I try to find the placeholders for this situation :

Hors-série avec Didier Sicard (22-12-2020)_Arte_2020_12_22_20_07.txt
Nos cerveaux menacés - Peut-on faire renaître le désir d'Europe (05-03-2019)_Arte_2019_03_05_20_05.txt
Rodolphe Burger - Moraliser la vie politique (29-07-2020)_Arte_2020_07_29_20_07.txt

Hors-série avec Didier Sicard_Arte_2020_12_22_20_07.txt
Nos cerveaux menacés - Peut-on faire renaître le désir d'Europe_Arte_2019_03_05_20_05.txt
Rodolphe Burger - Moraliser la vie politique_Arte_2020_07_29_20_07.txt
It means that the substring to remove is always at the same place from the end, and always with the same length. But as you can see the strings can have very different lengths.
For the moment, the only solution I have found in the help to get the final strings is this:
[N-500-36][N-22-]
where the number 500 is here only to tell "downward to the beginning", knowing that none original filenames won't ever reach 500 characters.


It seems that there is no other solution out of this one that I have found above. Could you confirm?
Thanks a lot!
Jacques