<do> element is simply a way to specify
some arbitrary type of control for the browser to make available to
the user. This can be rendered as a graphical button (as many PDA
browsers do), as an item in a menu (as most cell phone browsers do),
or as just about anything the user can know about and interact with.
This can even include things such as voice commands for a hands-off
WAP browser (in a car, for example).
<do> element contains nothing but the task
to be performed when the element is activated.
Specifies the type of this
This serves as a hint to the browser about the action this element
triggers and may influence how the browser chooses to present the
element. The following values are defined (undefined or unrecognized
types are treated as if they had been specified as
Acceptance of something. cell phones often bind this to the
“yes” key if there is only one
<do> of this type in the card.
Navigation backwards in the history stack (a
<prev> task or something similar).
Request for some sort of help. The help provided can be context-sensitive.
An operation that clears or resets the state of the interaction; for
example, a “clear and start over” operation on a group of
text fields or an operation to deselect all options in a
A context-sensitive request for additional options; for example, a button to bring up an “advanced options” menu.
Delete a single item or choice. To delete all items, use the
reset type instead.
unknown(or empty string)
A generic element that doesn’t fit any existing category.
Experimental types. The exact behavior of these is undefined. Some browsers may implement some of these for development purposes. These types shouldn’t be used in production systems.
Vendor-specific types. Some browsers may implement specific
<do> types of this form. Using these types
allows you to enhance your WML for a specific browser, while
remaining portable to others (unrecognized types are treated as if
they were specified
label(optional variable string)
Specifies an optional text label for the element. For example, a
browser that displays
<do> elements as
graphical buttons can use this as the button’s text. The WAP
specifications recommend that to work well on the widest possible
variety of browsers, this string should be limited to no more than
six characters, but this rule isn’t enforced.
Specifies the name of this element, for the purposes of shadowing (see Chapter 6, for more on shadowing). This type has no other effect.
optional(optional boolean; default
If set to
true, informs the browser that it can