Urlencode vs htmlentities

["Mark Steudel" <mark@xxxxxxxxxxxx>]

Lets say I have the following:
 
Current URL: http://www.domain.com/page.php?action=list
<http://www.domain.com/page.php?action=list&top=/page.php?action=list&id=3>
&top=/page.php?action=list&id=3
 
$top = $_SERVER['PHP_SELF'].'?'.$_SERVER['argv']['0']
 
Now I want to create a URL with a return link in it
 
<a href="'.$_SERVER['PHP_SELF'].'?action=add&amp;return='.$top.'"> Add
Something </a>
 
Should I use htmlentites on $top first?
 
Second let's say instead of constructing a link I want to use a header and
redirect someone
 
header("location: page.php?action=add&return=".$top );
 
So do I use urlencode here?
 
Lets say I have something that has been htmlentitied, and I want to use a
header command, do I htmlentitydecode and then urlencode?