All input elements with a type of "image" should have an "alt" attribute, and that attribute should be as short as possible. This test will fail if the "alt" text is over 100 characters long.

Example

Wrong

<input type="image" name="search" src="select_home.png" alt="Select this as a house which you would consider purchasing at a later time if it might strike your fancy to do so."/>

Right

<input type="image" name="search" src="select_home.png" alt="Select house"/>