- From: Charles McCathieNevile <charles@w3.org>
- Date: Wed, 16 Dec 1998 15:50:55 -0500 (EST)
- To: WAI UA group <w3c-wai-ua@w3.org>
(I am summarising several people's views here. If I have got something wrong, please explain on-list) Kathy suggested that we declare this as explicitly relevant to browser-specific functions, and create a similar formulation for functions specific to the rendered content in section 4 or 5. Although this is not my preference, I don't strongly object. Jon asked a bunch of pertinent questions, and suggested I try to clarify my thinking about this guideline to the group. And Al said that providing an interface was not sufficient to make a browser accessible, and was in any case handled by Assistive technology. (That is the bit I feel most likely to have misconstrued, but here goes...) As I understand it the reason Jaws works so much better with MS Explorer than with Netscape is that Explorer exposes an interface itself, whereas Netscape relies solely on the interface exposed by the underlying operating system. The fact that there is an interface exposed by the underlying operating system is sufficient to expose most of the functions, and therefore goes most of the way to satisfying 3.1.1. Explorer does better, not only in exposing functions like the ability to swap between frames, but in exposing features of the document, which are not functions provided by the browser itself, through an interface. The example of this which is probably most familiar is table reformatting - although Explorer itself does not allow reformatting of tables, it does provide that ability via an interface, in this case one which is built into explorer rather than the underlying operating system (if I recall correctly). Where both currently fail miserably is in providing access to certain functions related to the document. For example, it is possible to associate an event with a List Item using the onMouseOver attribute. However, there is currently no ability in most standalone browsers (as opposed to browser/editors) to give the focus in a device independent manner to a List Item. (In plain language this means that major browsers can't put LI into the tabbing order). So far the problems are addressed by the guideline that says (more or less) 'let users navigate to event triggers' But having got there (perhaps by using a tab-order - that is an implementation-specific detail), there is currently no way for most browsers to trigger the onMouseOver event, except with the specific device it addresses. For Assistive technology, commonly used to provide alternative control mechanisms, what is required is the means to do these two things. It may be that the Operating system provides an interface for the assistive technology to reproduce the motions of the mouse, and that the User Agent then fires the event, because it thinks there is a mouse over the point in question. In which case the problem is solved. Or it may be that the User Agent itself provides such a capacity. There are several parts to solving this kind of problem. One is that the event model in HTML is deficient. That is a matter to go from here to WAI Protocols and Formats, and from there to the HTML working group, at the end of which the events will hopefully all be specified in ways which are not tied to specific devices. (Enter onActivate as a real piece of HTML). Another is that the Operating system, or the User Agent itself, can provide some interface which allows the moouse to be 'mimicked' as described above. This is not impossible - Jaws already uses some kind of interface to provide a second cursor which can get to any part of the rendered document and trigger a Jaws-specific event - reading. What I have not addressed here is Jon's question about whether everyone (Info kiosks, screen readers, etc) needs to be bound by this requirement. The short answer is no, but I will give a longer answer in a seperate email later tonight. Cheers Charles --Charles McCathieNevile - mailto:charles@w3.org phone:(temporary) +1 (617) 258 8143 http://purl.oclc.org/net/charles W3C Web Accessibility Initiative - http://www.w3.org/WAI 545 Technology sq., Cambridge MA, USA
Received on Wednesday, 16 December 1998 15:50:57 UTC