This attribute specifies the number of Permanent Logical Channels
that are supported on this X.25 interface (that is, the number of
PermLcn components that may be provisioned at this interface).
The PermLcn components use channel numbers starting from 1 and
up to lowestILChannelNumber.
A value of 0 for this attribute indicates that no Permanent Logical
channels are supported on this X.25 interface.