This property is a strange and very specific Microsoft beast. Microsoft,
beginning in Windows 2000, has the ability to turn off its system
underlines for accelerator keys until the ALT key is pressed (then the
accelerator underline hint is displayed.) This property should have no
effect in previous Microsoft OS versions, and if this system capability
is turned off (or "on", depending on how you look at it), it will also
have no effect.
While this works for underlined elements (the HTML "U" element), it
also seems to work for any element, although a different pseudo-underline
color seems to be generated in such cases.
The element contains an accelerator key sequence.
[ IE5 ]
The element does not contain an accelerator key sequence.