C:\myperl\temp>perl temp.pl -z
$opts{z} = ""

C:\myperl\temp>perl temp.pl -y
$opts{y} = "1"

C:\myperl\temp>perl temp.pl -y -z
$opts{y} = "1"
$opts{z} = ""

C:\myperl\temp>perl temp.pl -z -y
$opts{z} = "-y"

C:\myperl\temp>temp -z -z
$opts{z} = "-z"