The structure of online help follows the hypertext principle; this means, you can read the text not only sequentially, but you can jump from a section to another one and each topic text has to be independent from the others, because it is never clear where the reader is coming from. This "jumping" is possible because of internally coded cross-references which are usually shown in the help text underlined and in green or blue. Online help is normally composed of several single files. The help program itself offers:

• Table of contents: Tables of contents contain all help topics organised according to different categories. Thanks to the hyperlink principle, users can go to a specific help topic by simply double-clicking.

• Indexes: They enable to enter key words to search for the corresponding help topics which, if found, are shown.

• Search function: This function allows to search for a single word or a multiple word expression contained in the help texts

• Help topics: Help topics are shown in windows which consist of a title bar, a menu bar, a button bar with buttons to browse through the help documentation, and a text field