Understanding pack() and unpack()

I'm trying to understand the pack() and unpack() functions because I think they might be of some use to me. However, I'm not able to get it to work right. I either get an error message saying that I've too few parameters to the pack() function or I'm getting nothing from the unpack function. Here is my test code: page1.php3 <script language="php"> $getVars = pack( "h*", "group=one&user=bob&this=that" ); header( "location: page2.php3?args=$getVars" ); exit(); </script> page2.php3 <script language="php"> echo "args: $args<br>\n"; $getVars = unpack( "h*", $args ); echo "Vars: $getVars<br>\n"; </script> What am I doing wrong? I'm just not 'getting' the documentation... :( Chris