Image for popup calendar needs alt text

Images used as form controls—such as graphical buttons used to submit forms—require a textual representation of their function. If this representation is missing, a visually impaired user may be unable to determine what function activating the control serves

The above is an extract from the WCAG guidelines and in this case applies to the calendar icon used as the date-picker on date fields. The element already has a title, can't imagine it would be terribly difficult to duplicate this into the alt text attribute so that government entities using this module can remain in compliance with accessibility mandates.