$ cat test-noCDS.pl
#!/usr/bin/perl -l
print "\x{101}";

$ cat test-withCDS.pl
#!/usr/bin/perl -l -CDS
print "\x{101}";

$ perl -l -CDS -e 'print "\x{101}"'
Ä

$ perl -CDS test-noCDS.pl
Ä

$ perl test-withCDS.pl
Wide character in print at test-withCDS.pl line 2.
Ä

$ ./test-withCDS.pl
Ä