When the result of a PAD tag is false the part after @else@ is used.

HTML RESULT 
{if 2 > 1}
  true
@else@
  false
{/if}
true
{if 1 > 2}
  true
@else@
  false
{/if}
false

The @else@ construct is a general feature of every PAD tag, it applies to all PAD tags.

PHP
constructs/else_4.php 		HTML
constructs/else_4.pad 		Result 
<?php

  $myVar = FALSE;

?>
 
{myVar}
  true
@else@
  false
{/myVar}
 false
When the result of a PAD tag is an empty array the part after @else@ is used.

HTML RESULT 
{data 'myArray1'}
  [1,2,3]
{/data}
{myArray1}
  Occurence {$myArray1} <br>
@else@
  No occurences
{/myArray1}
Occurence 1
Occurence 2
Occurence 3 
{data 'myArray2'}
  []
{/data}
{myArray2}
  Occurence {$myArray2} <br>
@else@
  Nothing to see here
{/myArray2}
Nothing to see here

The @else@ context can also be given with the 'else' option at the tag itself.

HTML RESULT 
{data 'myArray'}
  []
{/data}
{content 'nothing'}
  Nothing to see here
{/content}
{myArray else='nothing'}
  Occurence {$myArray} <br>
{/myArray}
Nothing to see here
{if 1 > 2, else='nothing'}
  true
{/if}
Nothing to see here