[c-nsp] PCR VS TICKET

[Good One]

We are just in a process to launch our network ticketing application and evaluating some software. I just came across a software which create a ticket and then you can link that ticket to a PCR (just in case). What PCR stand for and why would you need that? Would be great if someone can point to a link or can write up some general terms you use in ticketing system.
thanks
regards,Andrew