Execute AP520 from external App on Iseries

There's no way to use OVRDBF to select records in DBAPCVI/DBAPCVC, as the IO server programs, the CDRIVER jobs, are running in different subsystem/jobs than the AP520 job launched by LAIBCH7.

Usually, you will load your invoice records into DBAPCVI/DBAPCVD with a unique or specific batch number to keep things separate. Then, before you run LAIBCH7, update the AP520 job def with your specific batch number. You could use one of the Lawson batch job APIs to update the job parameters, like U@LOADJOB, or just update the field PARAMS in the genlib/JOBSTEP file with some other method. The field PARAMS is one long text field, so hunt around to find the exact position of the Batch parameter.