This MIB module defines objects to configure and manage the
Variable Optical Attenuator (VOA) modules.

VOA modules are typically used to attenuate channels added
by a network element, in order to equalize the input power of
each wavelength before the multiplexed signal consisting of
all wavelengths is sent through an EDFA.  There may be
a separate VOA per channel, one VOA per band of wavelengths,
or one VOA for the pass through wavelengths.

VOA modules are also often used before terminating optical
wavelengths at optical receivers, in order to avoid receiver
saturation.

The VOAs may be present on various modules within the network
element, for example, on an Optical Add/Drop Multiplexer
(OADM) module, on the same module as an optical transceiver,
or on a separate module of its own.