It states in the Caesar.dat file that the information in the Code Parameter Data Table must match the CL570 Design Standard library in PDS. Which file should be updated or does it matter as long as they match?

CL570 is of the format:
0, B31.3 !default
1, B31.1
3, B31.3
4, B31.4
5, B31.5
8, B31.8
12, ASME NC
13, ASME ND
14, NAVY 505
15, CAN Z662
17, BS 806
18, Swedish 1
19, Swedish 2
20, B31.1 - 1967
21, Stoomwezen
22, RCC-M C
23, RCC-M D
24, CODETI
25, Norwegian TDK-6
26, FDBR
27, BS 7159
28, UKOOA
29, IGE/TD/12

While the Caesar.dat file is:
0, ANSI-B31.3 !default
10, ASME-I
11, ASME-III
12, ASME-VIII-1
13, ASME-VIII-2
20, ASME Fld Mets & AGA Rpt 3
21, ANSI-B31.1
22, ANSI-B31.2
23, ANSI-B31.3
24, ANSI-B31.4
25, ANSI-B31.5
28, ANSI-B31.8
29, ANSI-B31.9
32, BS806
38, API-2000
50, AWWA
51, DIN
61, BS3351

I believe both items are used on the PDS side of the fence to generate the neutral file. Once the neutral file is available, it can be passed to CAESAR II for conversion.

If you want to see a list of the codes supported by CAESAR II, pull up the Allowable Stress dialog and click on the "Code" Drop List.