RTRR Maximum numbers of versions and days to retain questions.

[jfk105]

Hello
I'd like to backup some data from nas to (EXT4) external device through Rtrr + Backup Versioning (pretty much a rsync job does).
I'd to backup some data for a 1 year rotation (365 days) keeping the daily situation (so I don't know how many version of a each files could have at the end of the year but I guess 365 is the limit because it's a daily backup for 365 days... or not?).

So I don't understand clearly what "Maximum numbers of version"s and "Days to retain" means.
It means maybe that I set "Days to retain" to 365 it keeps 365 different backups and then rotates? OK this will be ok.
What I have to set into "Maximum numbers of version" if I want unlimited versions of files? Which number: 0, nothing, -1, a larger larger number? Or simply 365...
Thank you in advance, J
PS:The Qnap Nas about rtrr questions in not the model in my sign... it's a Ts-253A with 4.3.3.0262 firmware installed.