Some values for RC are:
01 - No region name specified
02 - Bad line in file
03 - File not found
04 - Error creating file
05 - Error opening file
06 - Error reading file
07 - Error writing to file
08 - TXLOCAL invalid
09 - TXDIR invalid
10 - Region files directory invalid
11 - Messaging support module not found
12 - Utilities module not found
13 - File handling module not found
14 - System files directory invalid
15 - Resource definition file directory invalid
16 - Region directory invalid
17 - Environment variable too large