I found some points in docs/gnuplot.doc (1.1077), and some addtion. They are the followings:
1) may be typo,
2) insert line feed before the sentence followed by a tag (lines started '^' may be ignored by doc2XXX program,
3) add explanation for return value of sqrt(x) if x is a complex value,
4) change double quote to backquote,
5) add mttics section.
That is intentional.
Other fixes applied.
thanks