In order to use an unqualified "$x" in the caller, I had to code the "S" (S.pm) module thus (The examples provided above gave Syntax errors):

package S;

use strict;
use warnings;
use Exporter; #"require" works too, but use is more std.

our @ISA = qw(Exporter);
our @EXPORT = qw($x);

our $x = 999;
1;
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