initialization_vector what are they

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hi there,
i'm using perl to encrypt data and Java using to decrypt:
 
while i can get perl or Java to encrypt and decrypt successfully  encryptions 
that each has encrypted i cannot get perl to unencrypt something  that java 
encrypted.
 
My focus has turned to the initialization_vector as to be a possible  cause.  
what are they and what does the example below mean?   Presumably java would 
need the same initialization_vector setting?
 
any thoughts would be helpful..
pg

my $key  =  pack("H16", "0123456789ABCDEF");
use  Crypt::CBC;
my  $cipher = Crypt::CBC->new(  {'key'           =>  $key,
'cipher'          =>  'DES',
'iv'               =>  '$KJh#(}q',
'regenerate_key'  => 0,   # default  true
'prepend_iv'      =>  0,
'pcbc'            =>  1  #default  0
});


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