$ perl -wMstrict -MData::Dump -e' dd "0".."-1" '
(0 .. 99)
$ perl -wMstrict -MData::Dump -e' dd "1".."-1" '
()
$ perl -wMstrict -MData::Dump -e' dd "01".."-1" '
("01", "02", "03", "04", "05", "06", "07", "08", "09", 10 .. 99)
$ perl -wMstrict -MData::Dump -e' dd "90".."-1" '
()
$ perl -wMstrict -MData::Dump -e' dd "1".."xx" '
(1 .. 99)
$ perl -wMstrict -MData::Dump -e' dd "11".."xx" '
(11 .. 99)
$ perl -wMstrict -MData::Dump -e' dd "90".."xx" '
(90 .. 99)
$ perl -wMstrict -MData::Dump -e' dd "-1".."xx" '
-1
$ perl -wMstrict -MData::Dump -e' dd "0".." -1 " '
(0 .. 9999)
$ perl -wMstrict -MData::Dump -e' dd " 0 ".." -1 " '
()
$ perl -wMstrict -MData::Dump -e' dd " 11 ".." -1 " '
()
$ perl -wMstrict -MData::Dump -e' dd "0.0".."-1.0" '
"0.0"
$ perl -wMstrict -MData::Dump -e' dd " 0.0 ".." -1.0 " '
()
$ perl -wMstrict -MData::Dump -e' dd "0.0".." 1.0 " '
"0.0"
$ perl -wMstrict -MData::Dump -e' dd " 0.0 ".."1.0" '
(0, 1)