Access can also be remote. When information is paper-based, you and the paper must be in the same location. When information is electronic, however, you can retrieve it from any remote location that has the necessary electronic tools—computers and telecommunications equipment.

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Note:  
The founders of SGML started developing markup languages in the late 1960s and early 1970s. At that time, it was becoming evident that computers and electronic information databases were here to stay.

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The goal is to share information databases conveniently and at a reasonable cost. CALS simplifies the document update and distribution process. It extends the life cycle of documents, and lowers the cost of using each document. It provides for interchangeability of documents and their segments, which lowers the cost of producing future technical manuals. Moreover, CALS promotes collaboration while allowing for competition by not compromising security.

The CALS SGML Standard and the Civilian World

Different agencies of the government have individual information needs, but they can benefit from sharing one another’s documents. Individuals are also like that. They benefit from sharing information and suffer when they don’t follow the same standards.

For instance, a medical student researching cancer in India could benefit greatly from the latest paper on the subject published by a scholar at Johns Hopkins University. Likewise, a physician at Johns Hopkins might find few case studies of a rare disease in the United States, but a doctor in India might have first-hand experience in assessing the viability of a recommended treatment.

If research is contained in SGML documents on the Internet, for example, relevant information can be tagged, linked, and accessed through hypermedia tools. The HTML standard is beginning to include ever larger sets of SGML features.

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Note:  
The World Wide Web is an SGML application. Application in SGML means a particular document type definition (DTD). Each HTML document on the Web is an instance of that document type. Using the rules of SGML, you can create an unlimited number of document types with features like the ones in HTML.

Version 2.0 of HTML is a revision of the HTML DTD. The proposed version 3.0 of HTML is yet another revision. Each revision so far has added more features of the SGML feature set. You can define as many document types as you want in SGML.

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Because civilians don’t have to worry about defense, they can distribute documents even more liberally than the CALS standard originally had in mind. In this way, they benefit greatly from SGML’s ability to make documents easily transportable to someone around the block or around the globe.

How SGML Makes Information Transportable

The challenge of dealing with different types of documents from many types of machines and software is not new. Many types of hardware exist—PCs, Sparc stations, Macintosh and other machines with Motorola processors, dedicated mini and mainframe computers, and niche computers with their own operating systems like Atari and Commodore. Different operating systems run on these systems. When you add differences among software to differences among hardware and operating systems, there are thousands of possible output types.

Originally, markup was what production editors did to manuscripts so that typesetters could apply the correct formatting, according to style conventions. It evolved through several electronic stages, from specific electronic markup that includes low-level formatting to generic markup that is flexible and not specific to any one environment.

Broadly speaking, there are three types of markup. They are described in table 1.2.

Hardcopy and Electronic-Specific Markup

Hardcopy electronic-specific markup work fine when you don’t need to share documents. Each system works because it does what is required:

•  It conveys formatting information, such as italics, bold, or uppercase.

•  It conveys typesetting layout information, such as margins, justification, and header or footer data.

•  It preserves the integrity of textual content.

The problem is that these systems often don’t work when you need to share documents. As long as you are working in-house and don’t need to communicate with other machines and people who follow different standards, you’re fine.

The world has changed, though. Everyone is sharing information. You need something better and less specific to a single environment. You cannot take a hardcopy markup, shown in figure 1.2, and send it along with electronic copy to someone around the planet. It is awkward to mark up someone’s Interleaf for Sparc Station document so that it runs on your PC—without SGML, that is.

Fig. 1.2  Hardcopy markup.

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Note:  
The disadvantage of these specific systems is that they are machine-dependent. That is, they depend on a single machine or a type of machine. In a way, they are on life-support systems. As soon as you unplug them from their host hardware or software, they die.

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