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8. SGML's Limitations for Web Delivery

To replace or even supplement HTML for Web delivery, SGML poses some significant roadblocks. The following paragraphs explain why.
No mainstream browser support The primary problem is that SGML never caught on with the mainstream browser providers. Microsoft Internet Explorer and Netscape Navigator do not contain any support for SGML. The reason for this goes hand-in-hand with what makes SGML so valuable: SGML offers so many options that designing tools to support them all results in complicated software. Even the premiere SGML tool providers, such as ArborText, do not support 100 percent of the options that the SGML standard allows.
With only HTML support available in the browsers, organizations wishing to publish their SGML information on the Web typically apply an automatic SGML-to-HTML conversion to their data. This produces acceptable results for simple viewing applications, but at the cost of "dumbing down" the data so that interchange and automation are much more difficult.
The reason for these difficulties is that the down-conversion from SGML to HTML results in a significant loss of information. Without that information, its virtually impossible to reconstruct the original meaning of the SGML files by looking only at the HTML file.
An analogous situation occurs when you convert a CAD drawing into a GIF file for viewing on the Web reconstructing the original CAD file from the GIF file is virtually impossible for all but trivial examples.
No support for styles Another barrier to using SGML for Web delivery is that SGML only standardizes structure; SGML does not include any support for styles. There have been a couple of attempts to establish a stylesheet standard, most notably FOSIs (Formatting Output Specification Instances, a standard originally developed by the U.S. military) and DSSSL (Document Style Semantics and Specification Language), but each of these has received little or no vendor support. The result is that there is no widely accepted standard stylesheet format for expressing SGML information.

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