Although many CD-ROM disks produced for viewing by computers of different platforms (Windows, Macintosh and UNIX) rely on Adobe Acrobat, the experiments recounted here used HTML. A brief discussion of these two alternatives, each of which offers advantages not provided by the other, can clarify the choice.
Adobe Acrobat files usually have the extension PDF (portable document format). In a sense, Adobe Acrobat competes with HTML in that PDF files can be viewed with a WWW browser that has been configured with an appropriate plug-in. Adobe, however, styles Acrobat as complementary to HTML. Adobe Acrobat permits much more control over the appearance of a document than does HTML, which leaves the details of the appearance of the document largely up to the browser. Consequently, the appearance of a particular HTML document can vary greatly when it is viewed with different browsers on different machines. The appearance of Adobe Acrobat documents tends, in contrast, to be much more consistent when viewed on different machines.
The Adobe Acrobat viewer, however, does include impressive search capabilities. Specifically, the Acrobat viewer makes it easy to search across all Acrobat documents, on an entire CD-ROM for example, for a particular text string. HTML browsers, on the other hand, can search only a single HTML file for a particular text string.
Because Adobe Acrobat is based on Adobe Postscript, Acrobat files tend to be larger than HTML files. To counteract this tendency, Acrobat includes built-in file compression. The file compression feature, of course, can put a greater burden on the processor in a machine used to view Adobe Acrobat documents than in one used to view HTML documents.
Although viewers for Adobe Acrobat documents are available at no cost from Adobe for all major operating systems, authoring Acrobat documents requires purchase of special authoring software from Adobe. Inexpensive, or free, HTML authoring tools are available, in contrast, from numerous sources.
Because of the availability of authoring tools and because of its richer capability for interactivity, HTML is likely to be preferable for author-prepared documents, especially those that include multimedia. That is, HTML is likely to be preferable for contributions to professional journals that rely on individual authors to supply material that will be published on the WWW or on a CD-ROM.
HTML's main shortcoming for this application has been its lack of a
standard for representing
mathematical symbols and equations.
At present, Adobe Acrobat permits equations to be displayed more
effectively than HTML. Discussion of proposed standards for displaying
mathematical equations and symbols in HTML documents is available
Up-to-date information about Adobe Acrobat is available at: