PDF: The companion to HTML

PDF (Portable Document Format) files are a useful alternative to Hypertext Markup Language (HTML) files for the presentation of technical information and other situations where a mix of text and graphics is required. PDF is not a substitute for HTML because PDF files do not have the key hypertext feature: the ability to link to another document.

PDF files contain the same kind of information as do files which are sent to a printer. When a PDF file has been stored on a Web site and linked to a HTML file, it can be viewed, printed and copied. Normally it cannot be modified. If you want to view a PDF file, you need to install a program such as Adobe Acrobat Reader, available from Adobe Systems Incorporated at "www.adobe.com". Use of this reader is free, but use of software to create PDF files is not.

The use of PDF files is becoming widespread because of the limitations inherent with HTML. HTML was created to display text documents using a Web browser and provide links to other documents over the Web. One feature of Web browsers is the ability of the user to control the size and appearance of the text displayed in the browser window by selecting both the font size and the font itself. Graphics are displayed in a format defined by the creator of the HTML file. In many cases, there is no problem with this different treatment of text and graphics.

If you wish to create technical documents that contain equations, the equations are normally created using an equation editor which defines a graphic's frame or box and provides commands to enable you to select and position the various elements of the equation according to certain conventions. Many technical authors use their favorite word processor with an equation editor to produce technical papers. Traditionally, these have been printed on paper. Some of these papers are now being published on the Web. If you convert the word processor file to HTML, the equations are converted to GIF files.

If you want to use special characters -- Greek symbols, for example -- you have to create one-character equation graphics files. You can do this and create a pleasing printed document by appropriately sizing and placing each of these graphics within the text. However, the Web version of this changes the relative size and location of the embedded equations and special characters. This is compounded by the ability of the viewer to use different fonts and font sizes.

The clean solution is to create a PDF file and be sure you, as the author, are satisfied with the appearance before you "publish on the Web." You'll know that the appearance you intended will remain for all viewers.

To create a PDF file, you need to follow six basic steps:
    * create your word processor document;
    * save your document as a postscript file;
    * convert the postscript file to a PDF file;
    * upload the PDF file to your Web site;
    * link this file to your Web page; and
    * test by viewing with Acrobat Reader.

CREATE your document using your usual word processor. If you normally use a postscript printer, follow your usual pattern. Otherwise take extra care, in the form of the steps that follow, because when you select a different printer you sometimes find that character and line spacings are slightly different and your page may be reformatted.

If your document has several pages, leave a spare line at the bottom of each page. Generally, do not try to cram any line where the line termination is critical.

SAVE your document to a file in a postscript printer format (using a ".ps" extension) using the print-to-file command in your word processor. Before you do this the first time, if you do not use a postscript printer you will need to load a postscript printer driver. Follow the normal procedure for your computer/operating system or obtain the help of an expert if you cannot do this kind of task yourself. One word of caution: You may need to experiment with several different printer drivers before you find one that translates everything correctly.

CONVERT the postscript file to a PDF file. The way that I convert is to use a package called Acrobat Distiller that is included with the Adobe PageMaker CD-ROM. This program reads in postscript files and converts and saves them with the extension ".pdf". The first few times you do this you will likely want to read your just-created PDF file in Acrobat Adobe Reader and see how it looks.

You may want to use Adobe Acrobat or other Adobe products that are described on the Adobe Web site at "www.adobe.com".

UPLOAD your PDF file to the directory where you keep your Web pages. Use whatever method you normally use for uploading HTML files -- for example, File Transfer Protocol (FTP).

LINK your PDF file in exactly the same way you would link an HTML file, realizing your file has a ".pdf" extension instead of ".htm" or ".html".

TEST by clicking on the link to your PDF document. If you have already installed Adobe Acrobat Reader, the reader program will be automatically invoked and you will see your document displayed on the screen in an Acrobat Reader window. You will see a menu which allows you to move from one page to the next (if it is a multipage document), magnify a portion of the page and print all or one of the pages.