This relates to an old PR (122127)
It appears you can set the unit of a ppp profile under rc.conf with something like below. This isnt documented anywhere as far as i can see, and I had to work it out by reading the ppp rc script. Thats fine for me but not many others
An example in the /etc/default/rc.conf and in the handbook would be very useful
ppp_test_unit=0 <<<<< no docs
Updated 10.1-BETA and 10.1-RC versioned bugs to 10.1-STABLE.