More advice for the full screen mode.
Sivut toimivat riittävän hyvin MS IE 4.0+, Opera 5.x+, Netscape 6.0+/ vast. Mozilla ja Konqueror 3.x selaimilla. Yleisesti ottaen sivut toimivat parhaiten uusimmilla Opera selaimilla. Sivujen toimivuus vanhemmissa selaimissa on heikko, erityisesti Netscape 4.x kohdalla.

I list below all topic groups, which I have done according to subjects, which they handle. You can return to this topic group by using this menu and the link Table of topic groups on the top of the each page.

Total structure of documents


Attributes, declarations and comments

Elements can commonly have attributes, which are inside the start-tag of elements. Attributes have many tasks. For example they define the presentation of elements. Hyperlinks are primary done with the element A with some special attributes (href, id and name).

Because empty elements don't work as element containers, they can have some kind of content only by defining attributes. In some cases the element itself is replaced with the referred content. For example IMG elements are replaced with the images, which the attribute src refer (these kinds of elements are called as replaced inline (level) elements and other are of course non-replaced inline level elements).

Individual attributes have values. In a HTML 3.2 document the element P can have for example the attribute align="center", which means center this paragraph ([M][S][Pw]):

<P align="center">Here is an example of a paragraph, which have the attribute align="center".</P>

In order to better separate elements and attributes I write elements in upper case (like BLOCKQUOTE) and attributes (like style=" ... ") in lower case characters.

There is however two exception. The document type declaration is in upper case letters because of the common style. That doesn't belong actually to the structure of documents. It is not necessary to the browser. If the declaration has file name, it gives however to the browser the possibility to download the file into the memory of the computer. This information is however necessary for validator services and applications.

The declaration have the exclamation mark in the open delimiter (<!DOCTYPE ... >). W3C has created to standard document types DTD-files (Document Type Definition), where are declared all used attributes and elements, and where are also defined allowed element structures (as I have earlier explained, the definition language in HTML-documents is SGML).

It is like the ear-tag of a cow. The cow doesn't need an eartag, but the owner (and the authorities) needs it. Browsers know them without the declaration, but in principle just the document type declares the language, which the documents has been written.

A cow, which have eatags

XML documents might need document type declarations, because the author might made his own declarations. In XML-document is used another declaration (<?xml version="1.0"?>), which correspond the eartags of cows. When I refer to XML-elements I use always lower case characters.

Comments use following syntax, which I have also used in my examples (look at the conceptual scheme[S][Pw]):

/* this is a CSS-comment, which should be green with browsers, which can understand CSS-definitions */

Meaning of particles of documents

A simple HTML document consists of only elements, attributes and contents. I mean it primary ordinary text, which have own markup codes for certain characters (read the Footnote 1[S][Pw], if you want to know more about this matter).

Particles give to the document following basic meanings (I handle them in the priority order, which in my mind they had in the first HTML documents):

  • Content
  • Structure
  • Linking
  • Semantics
  • Presentation

The original idea of HTML is that it is primary semantics and structural language, not a presentation language even if some elements can be understood as presentational. The next section handles a little bit history of HTML.