The Browsers - Pro CSS Techniques - page 68

X-grade
“X-grade provides support for unknown, fringe or rare browsers. Browsers receiving
X-grade support are assumed to be capable. (If a browser is shown to be incapable—if it
chokes on modern methodologies and its user would be better served without decora-
tion or functionality—then it is considered a C-grade browser.)
X-grade browsers include all browsers not on the C-grade blacklist or the A-grade
whitelist. Approximately 1% of our audience receives the X-grade experience.
Summary: X-grade browsers are generally unknown, assumed to be capable, modern,
and rare or fringe. QA does not test, and bugs are not opened against X-grade browsers. ”
The Relationship Between A- and X-grade Support
“A bit more on the relationship between A and X grade browsers: One unexpected
instance of X-grade is a newly-released version of an A-grade browser. Since thorough
QA testing is an A-grade requirement, a brand-new (and therefore untested) browser
does not qualify as an A-grade browser. This example highlights a strength of the Graded
Browser Support approach. The only practical difference between A and X-grade
browsers is that QA actively tests against A-grade browsers.
Unlike the C-grade, which receives only HTML, X-grade receives everything that A-grade
does. Though a brand-new browser might be characterized initially as a X-grade browser,
we give its users every chance to have the same experience as A-grade browsers. ”
This is a terrific approach to determining browser support for your organization. It ensures
that all visitors get the core content of your site. It ensures that those users who live on the bleed-
ing edge aren't penalized for their use of the latest beta release of their favorite browser. It ensures
that the visitors using Netscape 4 on an old 486 PC with Windows 95 doesn't see a broken layout
that obscures their ability to read the text. And it gives you, the web designer/developer, a steady
target to shoot at when it comes to browser support.
Yahoo!'s browser grading chart has been made public, and you can find it at http://
developer.yahoo.com/yui/articles/gbs/gbs_browser-chart.html . While using their chart
directly may work fine for your organization, you may also find that you need to come up with
your own chart, grading the browsers based on the criteria that matter most to you so that you
can draw your own lines between grades. The beauty of this sort of system is that no matter where
you draw those lines, you won't be cutting off anyone—now or in the future—from receiving
the content of your site. Just like television.
Appendix C includes a version of the browser-grading chart that we think is appropriate
for most general-use web sites and applications. It may not work for your organization with-
out some modifications, but it should at least provide you with a good start toward your own
grading system.