Expert: Concise Systems/Laird Scranton - 8/10/2010

Question
Want to know which type of subfile the Display file contains, without seeing the DDS or RPG program.

Answer
Using native iSeries or AS/400 programming, I'm not aware that subfiles are categorized by type, although there are three basic approaches to the use of subfiles.  However, that may be different in web-based applications or with web-based programming languages.

The main native-mode options for discovering information about a file without looking at DDS or a source program are to display file description information (DSPFD) or object information about the file (DSPOBJD). It's possible that there is a designation given when you use those commands that could be referenced.  

Theoretically, if you could determine whether the maximum number of records for the subfile matches the subfile page size, then it must be a single-page subfile.  If the maximum records is 9999, then the program is likely to take a load-all approach to handling records in the subfile.

From a traditional native perspective, all compiled subfiles look alike - it's only how a programmer chooses to use them that is different.

- Laird