the docs refer to
Environment variable.
Such variables are an OS thing. Perl lets you to access and modify them via the special variable
%ENV as explained in
perlvar.
The module has many defaults that can be set via environment variables or directly.
HtH
L*
There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.