Description: Starts, stops (aborts) a test in progress or clears the 
test results. The agent will only start a new test, if no
test is active on the targeted port. The value of this
object returns 'ready' when read, the value cannot be set
to 'ready'.
The cXdslTestTrigger value affects cXdslTestStatus as 
following:

     value   current TestStatus -->  new TestStatus
     -----   ------------------      --------------
     start   inactive/pass/fail/     active
             aborted
     stop    active                  aborted
     clear   pass/fail/aborted       inactive

All other combinations will result in error, for instance,
starting a test may fail due to a test already in progress.
Likewise, stopping a test NOT in progress will result in an
error.

The value of cXdslTestType, cXdslTestStatus and cXdslTestTime
will remain in the system until cleared or until the the agent
is reset.
When this object is set to 'clear' the test results are cleared,
cXdslTestType is set to none and cXdslTestStatus is set to
inactive. The 'old' test results will remain until completion
of a 'new' test if test results are not cleared