A role represents a functionality characteristic or
capability of a resource to which policies are applied.
Examples of roles include Backbone interface, Frame Relay
interface, BGP-capable router, web server, firewall, etc.
Valid characters are a-z, A-Z, 0-9, period, hyphen and
underscore. A role must not start with an underscore.
A Display string consisting of a set of roles concatenated
with a '+' character where the roles are in lexicographic
order from minimum to maximum.
For example, a+b and b+a are NOT different role-combinations;
rather, they are different formating of the same (one) role-
Notice the roles within a role-combination are in lexicographic
order from minimum to maximum, hence, we declare:
a+b is the valid formating of the role-combination,
b+a is an invalid formating of the role-combination.
Notice the need of zero-length role-combination as the role-
combination of interfaces to which no roles have been assigned.
This role-combination is also known as the null role-combination.
(Note the deliberate use of lower case leters to avoid confusion
with the ASCII NULL character which has a value of zero but length
The storage type for this conceptual row.
Conceptual rows having the value permanent(4) need not
allow write-access to any columnar objects in the row.
This object may not be modified if the associated
policyInterfaceStatus object is equal to active(1).