Basic question on spark advance tables

[Marteney, Steven J.]

I've been reading Programming 101 and Tuning Tips and have a quick question
on spark advance values.  In the Units section, the spark advance equation
is given as X * 90 / 256, with units from 0 to 90 degrees.  However, in the
sample spark advance table there are negative values.  Is the hex code in
the table standard signed, two's complement notation (MS bit set means
negative).  If so, this means the range of possible DECIMAL values is
actually -128 to +127, with units of -45 to +44.6 degrees.  Is this correct,
or did I miss something?

Steve Marteney
smarteney at xlvision.com