Alan wrote:
Now to deal with the specifics of your question, our best demonstration of
examples 6 and 7 (and also example 23 at which shows a subset of
the large number of unicode mathematical symbol possibilities that are
accessible with TrueType fonts) was done with the Debian ttf-freefont
package which is described as follows:

Thanks Alan! The Debian ttf-freefont is great and now, I can access to the same table than with
the Hershey font (and plplot looks nicer than ever)

A last issue: the alignment of the font seems different (by default) than with Hershey: the symbols
do not seem to be center in the $,$y position and the x/ylabel of written over the ticks.... ?
(this is a tiny effect)

Is there here again an environment variable to set?