Because IE will not transmit files with estension '.pl', all example Perl files are stored without extension. Be sure to add the '.pl' extension (or change the '.txt' extension to '.pl') when you save these Perl files in your local folder.
Simple example of a package, from sec. 22.1 and the Perl program that tests it
Simple example of a module, from sec. 22.2 and the Perl program that tests it
Example file I/O not using the FileHandle module, from sec. 22.3.1 and the input file used by it and the next program
Example file I/O using the FileHandle module, from sec. 22.3.1