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

WML Tasks

A task specifies what action to perform when an event, like entering a card or selecting a link, occurs.

Go Task

The <go> task represents the action of switching to a new card.

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

<wml>
<card>
<p>
 <anchor>
  Go To Test
  <go href="test.wml"/>
 </anchor>
</p>
</card> 
</wml>

Prev Task

The <prev> task represents the action of going back to the previous card.

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

<wml>
<card>
<p>
 <anchor>
  Previous Page
  <prev/>
 </anchor>
</p>
</card> 
</wml>

Refresh Task

The <refresh> task refreshes some specified card variables. If any of the variables are shown on the screen, this task also refreshes the screen.

The example below uses an <anchor> tag to add a "Refresh this page" link to the card. When the user clicks on the link, he or she refreshes the page and the value of the variable x will be set to 30:

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

<wml>
<card>
<p>
 <anchor>
  Refresh this page
  <go href="thispage.wml"/>
  <refresh>
   <setvar name="x" value="30"/>
  </refresh>
 </anchor>
</p>
</card>
</wml>

Noop Task

The <noop> task says that nothing should be done (noop stands for "no operation"). This tag is used to override deck-level elements.

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

The example below uses a <do> tag to add a "Back" link to the card. When the user clicks on the "Back" link, he or she should be taken back to the previous card. But the <noop> tag prevents this operation; when the user clicks on the "Back" link nothing will happen:

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

<wml>
<card>
<p>
 <do name="back" type="prev" label="Back">
  <noop/>
 </do>
</p>
</card> 
</wml>

Task Elements

Start tag	Purpose	WML
<go>	Represents the action of switching to a new card	1.1
<noop>	Says that nothing should be done (noop stands for "no operation"). Used to override deck-level elements	1.1
<prev>	Represents the action of going back to the previous card	1.1
<refresh>	Refreshes some specified card variables. If any of the variables are shown on the screen, this task also refreshes the screen	1.1