In contrast to NRZ mode, there is no fix association between the logical bit
value (e.g. 0 and 1 for 2-level patterns) and the voltage level at the output in
arbitrary bit shape mode. Instead of the simple logical bit value to output
voltage mapping, an arbitrary waveform is being used to define the
transition from one voltage level to the next one.
For a 2-level pattern, there are 4 different transitions (0 0, 0 1, 1 0,
and 1 1), for 3-level patterns there are 9 possible transitions and for 4-
level patterns there are 16 transitions that need to be defined.
Each type of transition is selecting the shape of the following bit. The bit
shape is defined as an arbitrary waveform with up to 64 points. The bit
shape editor is separating the several bit shapes by vertical lines. The
possible bit shapes are ordered in a way that all bits that are coming from
the same logical bit value (e.g. 1) are kept together and inside that group,
the logical bit value (or level index) of the target bit is increasing (e.g. 0, 1, ‘.’
for 3-level patterns).
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