Description: A bit array that contains the value of the
front panel LEDs and the annunciator. This is
a packed bit string; each LED is encoded into
4 bits (a nibble). The first nibble is stored
in the high order bits of the first octet. The
second nibble is stored in the low order bits
the first octet, etc. However, the current
mapping is that the first three nibbles are
reserved, the fourth nibble has the value of
the 'annunciator', and the 'normal' LEDs start
with the fifth nibble. If the LED values are not
available, a zero length string is returned. The
following shows the meaning of each bit (bit 0 is
the least significant bit) when it has a value
of one:

  bit  meaning
  ---  -------
   0   green light
   1   yellow light
   2   blinking
   3   reserved