>perl -le"use open ':std', ':encoding(cp850)'; use if $ARGV[0], 'locale'; print sort 'a', chr(0xE1), 'b'" 0
abá

>perl -le"use open ':std', ':encoding(cp850)'; use if $ARGV[0], 'locale'; print sort 'a', chr(0xE1), 'b'" 1
aáb

##</code><code>##

>perl -le"my $s = chr(0xE1); print $s =~ /\p{Alpha}/ ?1:0"
1

>perl -le"my $s = chr(0xE1); print $s =~ /[\p{Alpha}]/ ?1:0"
1

>perl -le"my $s = chr(0xE1); utf8::upgrade($s); print $s =~ /[[:alpha:]]/ ?1:0"
1

##</code><code>##

>perl -le"use feature 'unicode_strings'; my $s = chr(0xE1); print $s =~ /[[:alpha:]]/ ?1:0"
0

>perl -le"use 5.012; my $s = chr(0xE1); print $s =~ /[[:alpha:]]/ ?1:0"
0