This attribute indicates the current mode of the IwfV42bis encoder.
This mode can be either:
transparent: A mode of operation in which compression has been
selected but data is being transmitted in uncompressed form.
Transparent mode command sequences may be inserted into the
data stream.
compressed: A mode of operation in which data is transmitted in
codewords.
The encoder switches between the two modes depending on
whether the data coming from the Date Terminal Equipment (DTE)
is suitable for compression. The data compression function
periodically determines the compressibility of the data based on a
comparison of the number of bits required to represent a segment of
the data stream before and after compression.