a simple number, in which the default start runlevels get that as the start
value and stop runlevels get 100 - value.
a hash like { 2 => [:start, 20], 3 => [:stop, 55] }, where the
service will be marked as started with priority 20 in runlevel 2, stopped in 3
with priority 55 and no symlinks or
similar for other runlevels