different "-" signs, irregular? display, different evaluation in long vs. double,
there are several horizontal 'dash' characters in the character set that gnumeric uses, as mentioned at: https://jakubmarian.com/hyphen-minus-en-dash-and-em-dash-difference-and-usage-in-english/ “‐”, “−”, “–”, and “—”, and the "-" i get from keying on my keyboard ...
gnumeric 'double' understands them as different, while 'long' evaluates them as 'all equal', except the last one.
that means either the text evaluation in 'long' is different to the one in 'double' -> compatibility problem, or I did something wrong in my installations of 'long' ...
for display of values gnumeric uses the short '-' ( from keyboard? ), but sometimes one of the longer figures: dependent on the cell format, and as far as checked synchronously in 'long' and 'double'.
written to file only short '-' is used ... as far as i have seen,
can't say if intentional, can't even say if meaningful, just spotted ...
[ <edit 2022-04-26>: re-spotted the problem, checked here and saw attachements unavailable, re-uploaded ]