I don't know, IE IE is the worst level for various web standards, but our website is tested with IE, huh, huh. See the comparison of IE Firefox and Opera, description: http://nanobox.chipx86.com/browser_support.php. The conclusion is this:
Summary
FeatureMsie 6Firefox 1.0 Opera 8html
94%
98%
98%
CSS 2.1
48%
76%
86%
Dom Level 3 Core
32%
54%
Of
167/187
52%
Of
176/187
Dom Level 2 Events
39%
96%
Of
63/70
96%
Of
63/70
Dom Level 2 HTML
93%
97%
99%
Dom Level 3 Load and Save
0%
0%
96%
Of
12/49
Dom Level 2 style
42%
82%
54%
Dom Level 2 Traversal and Range
0%
62%
Of
34/53
87%
Of
34/53
Dom Level 3 Validation
0%
0%
0%
Dom Level 2 Views
50%
100%
100%
Miscellaneous Support
33%
69%
61%
Total
39%
67%
73%
