From http://www.w3schools.com (Copyright Refsnes Data)

WML <do> tag

The <do> tag can be used to activate a task when the user clicks on a word/phrase on the screen.

A <do> tag can also be nested inside a <template> tag. The <do> tag will then apply to all cards in the deck.

Syntax

<do type="type">
..task..
</do>

Attributes

Attribute	Value	Description
type	accept prev help reset options delete unknown x-* vnd.*	REQUIRED. Defines the type of the "do" element
label	cdata	Creates a label for the "do" element
name	nmtoken	Defines a name for the "do" element
optional	true false	If set to true, the browser ignores this element. If set to false, the browser does not ignore this element. Default is "false"
xml:lang	language_code	Sets the language used in the element
class	cdata	Sets a class name for the element. The class name is case sensitive. An element can be connected to multiple classes. Multiple class names within the class attribute are separated by white space
id	id	Sets a unique name for the element

Examples

The example below uses a <do> tag inside a <template> tag to add a "Back" link to each card:

<?xml version="1.0"?>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN"
"http://www.wapforum.org/DTD/wml_1.1.xml">

<wml>
<template>
 <do name="back" type="prev" label="Back">
  <prev/>
 </do>
</template>

<card id="card1" title="Card 1">
<p>
 Hello World!
</p>
</card>

<card id="card2" title="Card 2">
<p>
 From W3Schools!
</p>
</card>
</wml>

Note

If a single <card> contains multiple <do> elements of type="accept", and these <do> elements are not named, WML might fail to compile and no page is displayed.

This is caused because the default name when no name is specified is the element type, in this case accept.

Complete WML Reference