SET INFO-FUNCTION TO TRUE  CALL "I$IO" USING IO-FUNCTION                    f                    mode                    result             GIVING returnCode  | 
f  | the file handle returned by OPEN-FUNCTION.  | ||
mode  | determines which result is returned.  | ||
-1  | returns the same information as the l_parms parameter of the MAKE-FUNCTION. result is in the format of "11111,22222,333" where:  | ||
1  | maximum record size  | ||
2  | minimum record size  | ||
3  | number of keys  | ||
-4  | returns the number of records in the file.  | ||
-5  | returns the 256-byte key translation table.  If no key translation table was specified, then the E_NO_SUPPORT error is set. In this case, this should be simply taken to mean that the native key ordering was used.   | ||
0 or greater  | a value of zero or greater indicates that information about a particular key is desired. '0' indicates the primary key, '1' indicates the first alternate key and so on. That key information is returned as "11,2,333,44444" where: ( third and fourth fields are repeated for each additional segment in the key)  | ||
1  | number of segments in key.  | ||
2  | "1" if duplicates are allowed.  | ||
3  | size of first segment.  | ||
4  | byte offset of first segment.  | ||
result  | depends by mode parameter.  | ||
>0  | Operation successful.  | 
0  | Operation failed.  |