When an input element has a pattern attribute, the title attribute may be used to inform the user about what is requested. This should be showed to the user via a tooltip when the mouse is hover for example. Note: I'm not really sure about the Product/Component so do not hesitate to change them if you think I'm wrong.
Actually, nothing has to be done: the default behavior is to show a tooltip with @title. So authors will have to be sure @title contains a description of @pattern.
Let's have a test for this.
Created attachment 460246 [details] [diff] [review] Test v1 This test is quite simple but I think there is no test checking that the tooltip is correctly shown for input elements.
Marking checkin-needed: a=test-only