This object indicates a mask for the corresponding instance of
ciapAllocatedAddress.
If the value of this column is all 1's, then the corresponding
instance of ciapAllocatedAddress denotes an IP address.
If the value of this column is not all 1's and the
corresponding instance of ciapAllocatedAddressType is 'ipv4',
then the corresponding instance of ciapAllocatedAddress denotes
an IPv4 subnet when logically ANDed with the value of this
column.
If the value of this column is not all 1's and the
corresponding instance of ciapAllocatedAddressType is 'ipv6',
then the corresponding instance of ciapAllocatedAddress denotes
an IPv6 prefix when logically ANDed with the value of this
column.