[support] upload : overwriting files

[pyg]

Hello Drupalers !

Simple question, but search & google didn't helped me : is it possible
for a user to overwrite an upload file ?

I tried to :
1. upload foo.txt (then submit)
2. delete foo.txt (then submit)
3. upload foo.txt (then submit)

but on the third step, file is named "foo_0.txt"

My users just want to update some pdf files wich public adress is
widely distributed.

Any clue on this ?

Thanks.
Pierre-Yves