With InterForm400 there is a command named the same as the library: APF3812. You can use this command to merge an overlay or overlay selector with a spooled file. In short this command does the same as function 1=Merge with overlay in Auto Forms Control, but there are some extra features with this command:

1. You can use the command to create a PCL stream file in the IFS. This PCL file can e.g. be sent to another site and copied directly to a printer – without having InterForm400 at the destination site. This is used in some installations for printing large spooled files (e.g. >100.000 pages) at an external printing company. Before sending the file it can also be compressed with the command, APF3812/ZIP.
2. You can build in the command in your own programs, so that immediately after creating the spooled file to be used for the merge, then you can run the command yourself and just refer to the last spooled file created by the current job – with a specific spooled file name.
3. You can use the command with OUTPUT(*VIEWER) in an interactive job to start up Swiftview and show the merged result immediately in your own applications.

The APF3812/APF3812 command generates only PCL output. If you want to generate ZPL (Zebra Printing Language) or IPL (Intermec Printing Language) in the same manner, then you should use the commands MRGSPLFZPL or MRGSPLFIPL. These commands can generate either a merged spooled file or a stream file.