Managing Serviceguard 14th Edition, June 2007

Planning and Documenting an HA Cluster
Package Configuration Planning
Chapter 4 175
HP recommends assigning values in increments of 20 so as to leave
gaps in the sequence; otherwise you may have to shuffle all the
existing priorities when assigning priority to a new package.
no_priority, the default, is treated as a lower priority than any
numerical value.
3. All packages with no_priority are by definition of equal priority,
and there is no other way to assign equal priorities; a numerical
priority must be unique within the cluster. See priority (page 286)
for more information.