No-display cards have a variety of uses, such as:
The examples provided so far in this manual use the ACCEPT action of no-display cards. However, a no-display card can also provide a PREV action. The phone executes the PREV action for a no-display card when the user navigates to the card via a CANCEL or a PREV task. For a complete list of the task types that can invoke a no-display card and the actions the phone executes in the no-display card, see the HDML Language Reference.
The following are some important considerations you should observe when you use no-display cards:
Because UP.Phones have relatively little processing power, loading any card, including a no-display card, takes time. Each no-display card slightly decreases the performance perceived by the user--even if it is cached in the UP.Phone. For this reason, avoid using more than two consecutive no-display cards.
No-display cards can complicate your service's navigation model and yield unexpected results. In particular, be very careful when you use no-display cards to navigate to nested activities. For example, the following HDML deck allows the user to navigate to a display card that he or she can't back out of.