bytes is used as follows:

$x = chr(400);
    print "Length is ", length $x, "\n";     # "Length is 1"
    printf "Contents are %vd\n", $x;         # "Contents are 400"
    {
        use bytes;
        print "Length is ", length $x, "\n"; # "Length is 2"
        printf "Contents are %vd\n", $x;     # "Contents are 198.144"
    }

8.29. blib		8.31. ByteLoader