A string of octets containing one bit per VLAN
for VLANS with 'VlanIndex' values of 3072 through 4095.
The first octet corresponds to VLANs with 'VlanIndex'
values of 3072 through 3079, the second octet to VLANs
3080 through 3087, etc. The most significant bit of
each octet corresponds to the lowest 'VlanIndex' value
in that octet.
When a bit is set to '1', it indicates the
corresponding tagged VLAN as active for this user.