From the Department Of Homeland Security's "Privacy Impact Assessment" :
Appendix B PNR Data Elements
PNR Data Elements May Include*
1. PNR record locator code
2. Date of reservation
3. Date(s) of intended travel
4. Name
5. Other names on PNR
6. Number of travelers on PNR
7. Seat information
8. Address
9. All forms of payment information
10. Billing address
11. Contact telephone numbers
12. All travel itinerary for specific PNR
13. Frequent flyer information (limited to miles flown and address(es))
14. Travel agency
15. Travel agent
16. Code share PNR information
17. Travel status of passenger
18. Split/Divided PNR information
19. Identifiers for free tickets
20. One-way tickets
21. Email address
22. Ticketing field information
23. ATFQ fields
24. General remarks
25. Ticket number
26. Seat number
27. Date of ticket issuance
28. Any collected APIS information
29. No show history
30. Number of bags
31. Bag tag numbers
32. Go show information
33. Number of bags on each segment
34. OSI information
35. SSI information
36. SSR information
37. Voluntary/involuntary upgrades
38. Received from information
39. All historical changes to the PNR
Read the full report here.