$ perl -MEncode -e '$o=encode("utf16","1234"); print $o' | xxd -g1
0000000: fe ff 00 31 00 32 00 33 00 34                    ...1.2.3.4

$ perl -MEncode -e '$o=encode("utf16le","1234"); print $o' | xxd -g1
0000000: 31 00 32 00 33 00 34 00                          1.2.3.4.

$ perl -MEncode -e '$o=encode("utf16be","1234"); print $o' | xxd -g1
0000000: 00 31 00 32 00 33 00 34                          .1.2.3.4