# Converts $s to use the UTF8=1 storage format if it's not already.
utf8::upgrade($s);

# Converts $s to use the UTF8=0 storage format if it's not already.
# Dies if it can't.
utf8::downgrade($s);

# Converts $s to use the UTF8=0 storage format if it's not already.
# Returns false if it can't.
utf8::downgrade($s, 1);

##</code><code>##

# From Unicode to UTF-8:
utf8::encode($s);
utf8::encode(my $utf8 = $uni);
use Encode qw( encode ); my $utf8 = encode('UTF-8', $uni);
use Encode qw( encode_utf8 ); my $utf8 = encode_utf8($uni);

# From UTF-8 to Unicode:
utf8::decode($s);
utf8::decode(my $uni = $utf8);
use Encode qw( decode ); my $uni = decode('UTF-8', $utf8);
use Encode qw( decode_utf8 ); my $uni = decode_utf8($utf8);