Data which are processed by one system cannot be used on another. Storing text in a machine-readable form raises expectations that cannot always be met. It is hard to explain to an author that text, which exists on a computer, needs to be retyped in a different format. Another problem with electronically stored information is that it is difficult to understand and retrieve. SGML conforming documents can be interchanged and processed on many different systems in many different ways.
Programs can analyze SGML texts because their structure is clearly indicated.
Hence computers can manage large amounts of complex data and provide easier access to these data. Traditionally, the only dimension of text is the paper it is printed on. Perhaps the most important property of SGML is its ability to add a new dimensionto information, since the latter becomes independent of the medium. This permits new kinds of processing. Storage is no longer restricted to paper, but could be in different forms such as in a database or on optical media.