Custom Variables

[SLESSARD]

I'd like to push some values in different FreeText Fields therefore by creating a variable XYZ_SUBJECT and being able to use it when needed would be created. I'm confident this is feasible and just not sure how within OTRS (config.pm?)

For example by adding Ticket::Frontend::AgentTicketAddtlITSMField###Subject: $Env{"Time"}
The following would appear 2011-02-16 12:52:25 under ITSM / note Subject

Is there a list somewhere that list every single variables ?
How can I define my own?

Thanks,