the both home versions sample
scripts WORKS on 2018c
The difference between 2018c
and today's git and snapshot
is :
git: a_eff and lagreg work and cause no problems
2018c : they work but cause "penetration"
In this case I would tend to leave the requirement at something
<= 2018c. Depending on how serious you think this spillover into
the global scope is (what you called "penetration"), you could issue
a clear warning to the users, for example in the help text and/or in
the printout.
For the printout, you could check the gretl version like this:
if $version < 20183 # earlier than 2018d
print "watch it!" # the warning (not this one!)
endif