Indicates the state of a particular jack.
Within a particular MAU, setting this to 'active' on
a jack which is not the current active jack will
deactivate the current active jack.
Setting the current active jack to 'active' has no
effect.
A value of inactive(2) indicates that the jack is
currently deactiveated. Setting this to 'inactive'
has no effect. Of all the jacks connected to a MAU,
at least one must be active at all times.