The following is a list of Circ logger (z309) action codes and their meaning.

00 - Log loan note            -
01 - Regular loan             -
02 - Offline circulation loan -
03 - Regular return
04 - Offline circulation return
05 - Loan deleted
06 - Late return
07 - Late recall return
08 - Late return within grace period
09 - Self check loan          -
10 - Self check return
11 - Staff renewal            -    
12 - Web renewal              -
13 - Batch renewal            -
14 - Self Check renewal       - 
15 - Courtesy letter created  -
16 - Overdue letter created   -
17 - Loan declared lost       -
18 - Loan claimed returned    -
19 - Online recall            -
20 - Batch recall             -
21 - Recall cancelled         -
22 - Due date changed backward-
23 - Due date changed forward -  
24 - Return date changed      
25 - Loan returned and placed in transit
26 - Self check cancel renewal-
27 - Self check cancel loan   
28 - Loan to sponsor
29 - Not On Loan Return
30 - In House Use
50 - Log cash note
51 - Cash transaction created          -  
52 - Cash transaction fully paid
53 - Cash transaction partially paid   -
54 - Cash transaction fully waived
55 - Cash transaction partially waived -
56 - Cash transaction exported         -
57 - Cash transaction imported         -
58 - Cash transaction updated to paid (batch)
59 - Notice to patron     
60 - Self check cancel return          - 
62 0000 L Fully paid for $1. Receipt number:$2.
64 0000 L $1 Note
65 0000 L $1 Note
66 0000 L $1 Note

Note:  the $aleph_root/error_eng file has additional information on certain of these types.