An entry contains information about one interface that
represents a group of DWDM channels. The group can be
described as a specified set of DWDM frequencies, or as the
group of all DWDM frequencies except for those in a specified
set.
If a frequency is included in a DWDM channel group, this does
not necessarily indicate that there is a signal present at that
frequency. It indicates that if a signal is present at that
frequency, then that signal is included in this DWDM channel
group.