This value mapping from HOST-RESOURCES-MIB would be useful to be included in default installation, because it is used in majority of SNMP devices.

The mapping is simple:

1 ? Unknown
2 ? Running
3 ? Warning
4 ? Testing
5 ? Down

And it's description from mib says:

The current operational state of the device described
by this row of the table. A value unknown(1)
indicates that the current state of the device is
unknown. running(2) indicates that the device is up
and running and that no unusual error conditions are
known. The warning(3) state indicates that agent has
been informed of an unusual error condition by the
operational software (e.g., a disk device driver) but
that the device is still 'operational'. An example
would be a high number of soft errors on a disk. A
value of testing(4), indicates that the device is not
available for use because it is in the testing state.
The state of down(5) is used only when the agent has
been informed that the device is not available for any
use.