PostScript is a printer format. The file cannot be changed by opening it in any program. Using Acrobat Distiller we convert the PostScript file to the PDF format. The PDF format is well known, relatively secure, and relatively easy for everyone to read on the Internet. It is also relatively easy to print PDF files.
Users can obtain a print-out that is, on the whole, identical to the printed document.
Authors who wish to write their document in the HTML format are free to do so - we also publish HTML files.