@Krux02 : I was also put on the wrong leg by the original question. But, looking more closely to the content of the program, it looks like _cdunn2001_ is dealing with DNA sequencing data. That is one of those exceptions. The alfabet used in such encodings is very limited (well within the ASCII range).
Files with such an encoding can easily be 40GB in size or more. Moving to UTF32 would increase the size to 160GB (or use an enormous amount of program memory). In such a case, it does add a lot of pain with no gain. So I understand that _cdunn2001_ is looking at the byte encoding in this specific case.
