Description: This object is used to provide access characteristics
pertaining to other objects in the given entity row.
The characteristics are divided into categories.
Each category uses a set of predefined bits to 
encode data.

The following categories are currently supported:

   Category                    Bits
   --------                    ----
   Community Access Rights     1..4
   Network Interface           5..6
   UNUSED                      7..15

The categories are orthogonal to each other, so it
is not necessary to perform 'inter-category' bounds
checking.

The object value is a concatentation of encodings
from each category, and can be considered a sum.
The actual encoding mechanism is defined on a per
category basis.

Categories
==========

Community Access Rights
-----------------------
Community access rights are associated with the community
name, internet address pair.  More than one access right
can be defined for a given community name, internet
address pair.

The encoding works as follows:  Starting from zero, for 
each access right supported, 2 raised to a power is
added to the sum.  The powers are according to the
following table:

           Type         Power
           ----         -----
           readOnly       0
           readWrite      1
           trap           2
           other          3

For example, a community name, internet address pair
with readOnly and readWrite access rights, would have
a value of 3 (2^0 + 2^1).

An access right of other(3) defines the entity row as
non-SNMP manageable.  Management information is provided 
in the chasEntityAccessMethod and the Network Interface
(defined below).

Note:  Just because a user directs a message to the community
       name, internet address pair does not imply that the
       user is authorized on that pair.  Additional security
       mechanisms may be employed such that only messages from
       particular internet addresses are authorized.

Network Interface
-----------------
The network interface is associated with the internet
address and defines the route for management traffic.
A network interface can be one of the following:

       none(0),
       obm(1),
       ibm(2), and
       port(3).

The value is placed in the 2-bits reserved for network
interfaces.

Note:  ibm(2) and port(3) are both in-band management.  The
       difference is ibm(2) is a module wide ip address, and
       port(3) is associated with a particular port/interface.