]> W3A/U -- WWW Applets/User functions API

W3A-U: User functions

User functions or accessories can perform such tasks as popping up a calculator, managing a hotlist, editing HTML files, adding remote control, and generally enhancing the user interface. They are started explicitly by the user, or automatically by the browser immediately on start-up. There is at most one instance of each user function.

User functions are, in principle, based on a subroutine model. They perform a function and then return. In the user interface this may correspond to a modal dialog. However, they may also open permanent windows and register event handlers for them, but some care is needed here.

User functions have a signature that includes:

  1. Zero or more labels (for use in a menu, or on buttons).

  2. Zero or more corresponding icons (which some browsers may display in preference to a button or menu entry).

  3. A list of object files.

  4. A suffix.

All user functions must define the following functions:

How user functions can handle events is explained in the next section, together with the other functions that make up the W3A API.