§1194.22(a) A text equivalent for every non-text element shall be provided (e.g., via "alt", "longdesc", or in element content).

Checkpoint
Is a graphical image used in place of a form button?

Explanation
Typical HTML-generated form buttons are rendered as gray rectangles containing whatever text you code into the tag. However, some developers prefer to use a custom-designed graphical image for aesthetics reasons. If necessary, search through the page's source code for an <input> tag that contains the attribute type of "image" and an src attribute that contains a URL to a graphical image (e.g. <input type="image" src="button.gif" name="submit_button" alt="search">).

Checkpoint
Does the image contain an alt attribute?

Explanation
A graphical image used as a form input button is treated exactly as any other graphic or button, in that assistive technology cannot identify its intended function unless an alt attribute is included.

Guidelines
Alt attribute descriptions for images used as form input buttons should, at the very least, list the same functionality that is displayed on the graphical image. However, because this graphical image leads to a function, it is strongly recommended that a brief description of what will happen when the user clicks on the button is included in the alt attribute.