[otrs] please, explain this to me

25 Feb 2008

      B.2.3.18. PostmasterX-Header

What does it mean this example?
Can I populate free fields with this?
Thank you in advance.
Daniele

Description:Module to filter and manipulate incoming messages. Get a 4 
digit number to ticket free text, use regex in Match e. g. From => 
'(.+?)@.+?', and use () as [***] in Set =>.

$Self->{'PostMaster::PreFilterModule'}->{'2-Match'} = {
'Match' => {
'Subject' => 'SomeNumber:(\\d\\d\\d\\d)'
},
'Set' => {
'X-OTRS-TicketKey-1' => 'SomeNumber',
'X-OTRS-TicketValue-1' => '[***]'
},
'Module' => 'Kernel::System::PostMaster::Filter::Match'
};