What is "File backup group" in post server scripts

Hello,
I am playing around with the post backup scripts.
I made a simple script to check all paramters:
echo $1 $2 $3 $4 $5 > /temp/a

The output of /temp/a is:
/media/BACKUP/urbackup/host/190215-1047 1 0

The third parameter should be “File backup group” which is 0 here.

I don’t really understand what this is. I thought it could be the group where the client is but 0 seems to be something else.

So what is meant by “File backup group” (in the Server Administration Manual?

Thank You

Is that not Settings | Groups (dropdown)
for grouping systems with different settings per group

It’s for virtual clients. See https://www.urbackup.org/backup_postgresql.html (last method) for example usage.