Um, buch.pl? I would have named it "order_books", at least if it's a command-line script. I fully agree with Abigail's statement about leaving off the .pl.

For web-based applications, I don't need to follow silly Win32 conventions about file-naming because I use mod_perl. I have modules like MySite/Controller/OrderBooks.pm and tie them to URLs like /books/order/, or whatever the marketing folks like the look of.