http://msdn.microsoft.com/en-us/library/ms533894(VS.85).aspx

Now that I (think I) understand what’s being discussed, I’m pretty sure this is not a good idea. A checkbox is either checked or unchecked. Whether a user has actively interfaced with a form element doesn’t really change this fact. If you set meaningful defaults in your form, you should have no use for this.

In the “Check All” example, the “indeterminate” state is suggested as ideal for when the “Check All” is not checked but some of the “child” checkboxes are. Since only some of the child boxes are checked, the “Check All” itself is KNOWN to be *unchecked* not indeterminate. The current paradigm is well known and understood by current users and the only thing added by an indeterminate state is confusion.

Like many others I’ve written javascript to handle the “Check All” control, in which a user manually checking all the children checkboxes automatically checks the “Check All” box as well. Or, if you want to earn some bonus points with your boss, have the original state of the child checkboxes restored when “Check All” is checked then unchecked (eg, half of the boxes are checked, you click Check All then uncheck Check All and instead of none of them being checked, half of them are).

Why not add this behavior to HTML5 so we don’t need to code it by hand? That would be far more helpful than tacking on bizarre features like “indeterminate”.

We should be working to simplify webforms to make them more accessible and easier to use, not adding complexity for its own sake.

are you sure? questionmark as end of a string?