If you direct the output from the Display Journal (DSPJRN) command to a database output file, you can further restrict the journal entries you want to process by creating logical files over the database output file.
Each journal entry occupies one record in the output file. Each has a fixed-length portion for standard files. Before-images and after-images occupy separate records. The ENTDTALEN parameter controls the length of the field that is used to contain the record image. The ENTDTALEN parameter also controls whether the field is a fixed or variable length field. If the journal entry is smaller than the output file record, the journal entry is padded with blanks. If the journal entry is larger than the output file record, the remainder of the journal entry is truncated, and the system issues a warning message. To avoid truncation, specify the maximum record length in your files for the ENTDTALEN parameter on the DSPJRN command or specify *CALC for the ENTDTALEN parameter to allow the system to calculate the length of the specific data field so no entry is truncated.
If you write journal entries to a database output file, you can write application programs that will process the data to:
If you remove all changes that were made by a particular program, you could remove some valid updates. For example, assume that two work station users are using the same program to update an object, and one user enters some data that is not valid. If you remove all invalid data changes that are made by that program, you also remove the valid data that is entered by the other work station user.