# Beyond the Semantic Web: Towards an Implicit Pragmatic Web and a Web of Social Representations
## 3 The Various Kinds of Web  
### The \"Syntactic\" and the Semantic Web  
#### 3.1.1 HTML and Its Evolution  
People usually connect the invention of the Web by [PERSON] with his internal CERN memo released in March 1989 [13]. However, the process started quite some time earlier with the invention of the generalized markup language (GML) by [PERSON] in 1969 [14]. GML later became SGML (S for \"standard\"), and still, later, XML. SGML, and, therefore, also its application HTML (hypertext markup language), is profoundly rooted in Chomskyan tradition. In SGML and HTML, a document is considered as a (formal) word in a (formal) language, the (formal) grammar of which is contained in a part of the SGML document called the DTD (document-type definition). An SGML document is a set of \"elements\" endowed with a tree structure based on the inclusion relation. At the leaf level of the tree, we have either empty elements (potentially with attributes) or text fragments. An HTML document, the basic unit of the first version of the world-wide Web, is an SGML document with a fixed DTD containing 18 element types (in its first version). The semantics of these elements represent a standard document structure (sections of various levels, paragraphs, tables, lists, images), typographical styles (italics, bold, underlined, etc.), hypertext links, etc. To be called an \"HTML document\", a document had to be _well-formed_, in the sense of respecting SGML syntax, and _valid_, in the sense of being a (formal) word in the formal grammar described by HTML's DTD. Usual actions on HTML documents were checking their validity, displaying them in a Web browser's window, and navigating through them.  
As the explicit structure of HTML documents was mainly syntactic, the original WWW was later called the \"Syntactic Web\" ([15] p. 5). Before we close this section on the \"Syntactic\" Web and move on to the Semantic Web, let us mention three features of the Syntactic Web that belong to the realm of the implicit:  
1. The alt attribute of the img tag (for inserting images), which was introduced in HTML v2 ([16] p. 34) (1995). This attribute was used to contain a hidden description of the image, described as follows: text to use in place of the referenced image resource, for example, due to processing constraints or user preference.
2. The acronym and abbr elements, introduced in HTML v4 (1999) ([17] Section 9.2.1). The title attribute of these elements is meant to contain the expanded version of the abbreviation or acronym (the distinction between abbreviation and acronym was irrelevant; therefore, the acronym tag became obsolete in HTML v5, while the abbr is still valid today). The part of the specification that justifies the existence of these elements is as follows: Marking up these constructs provides useful information to user agents and tools such as spell checkers, speech synthesizers, translation systems, and search-engine indexers.
3. The ruby element, introduced in HTML v5 (2011) ([18] Section 4.6.19). This element is useful for sinographic languages and adds an annotative layer above or next to sinograms (cf. [19] p. 822). When this layer is hidden through CSS code, annotation (or the main text layer) becomes implicit information in the Web page code.  
Finally, of course, since HTML is interpreted by Web browsers, any SGML or XML comment included in the Web page's code becomes implicit information, available only to those previewing the code.