Combined PDFs

Merge very often deals with data streams that have multiple documents' worth of data in them. Merge can produce an individual PDF for each document (record, transaction) in the data, and/or it can produce a 'combined PDF' of multiple documents into a single PDF. The latter is often used for archiving, for sending out to a print service bureau, or with bookmarks for looking up documents.

A combined PDF is produced by using the -PDFCombineDocuments Yes directive. That is in fact the default setting in the Default-PDF.prt configuration file.

So now you could have PDFs with lots of documents in them. DocOrigin encodes special markers and a special index section in its PDFs. These markers allow PDFExtract to know where the document boundaries are and, with the document index, is able to have direct access to any given document.
This is quite different from other PDF software where all you have is a great number of pages with no built-in understanding of which pages belong to which document.