#!/usr/bin/perl -wT
use strict;

my $v1 = my $v2 = "abcdef";

$v1 =~ s/c
d//x;               # original pattern: literal \n is gobbled by /x
                    # equivalent to the non-x: s/cd//;

$v2 =~ s/c\nd//x;   # deparsed version: interpolated "\n" is not touched by /x
                    # equivalent to the non-x: s/c\nd//;

print "V1 = '$v1'\n";
print "V2 = '$v2'\n";

=OUTPUT
V1 = 'abef'
V2 = 'abcdef'