What is the meaning of $normalize->{$1}

Hi,

I am trying to understand fully a perl program with the following lines:

   } elsif( /^(\#?\s*(?:pickup|qmgr)\s+)(?:fifo|unix)(\s+.*)/ ) {
      if( defined $normalize->{$1} ) { next; } else { $normalize->{$1} = 1; }
I do understand the first line, but I can not find what the second line is 
about. 

As far as can see the tested line in $_, from a file, is all ASCII with lower 
case characters. At the begin of the perl program the is no "use <something>".

-- 

fr.gr.

Freek de Kruijf