We currently implement these outputs as two PDF2 customization folders. One for the "book" output and the other for the simple/relnote outputs. We use a custom input parameter in the simple/relnote customization to differentiate between the two; they are nearly identical.
The vast majority of the code in the book customization folder is reused in the simple/relnote customization folder. We currently have copies of that code in both customization folders. If there were a way to reuse that code without copying it, it would be easier to maintain. Otherwise, if we adjust some base behavior in the book customization folder, we have to remember to copy the change into the same file in the simple/relnote customization folder.
If there is no DITA-OT mechanism to do this, I was going to rearrange the source tree for our PDF2 customizations into three folders, one for each output. Then, when we "build" our PDF customization plugins, we could pick and choose which files to copy into each customization folder. That way, the duplication only appears in the deployed plugins, not in our source tree.
Thank you for any input you may have.
Best regards,
Paul Anderson
Compuware Corporation
I would just merge the code and use modes to select the right templates basses in the type. this way you're only looking at one set of files and you can keep the variants relatively close for maintenance.