This option is intended to speed up printing on digital machines if it is possible to combine background PDFs and PDFs with variable data (numbering in our case). Terms "master", "form" or "powerform" are usually used to refer to background PDFs with digital printing machines. The possibility of using background PDFs is, however, a feature of the given printing machine and Montax Imposer cannot affect it. It is only able to prepare the background PDF if your machine has this feature. This background PDF (for example with a ticket design) is processed by the machine only once and it is merged with the variable PDF during printing, whose processing is usually much faster, because it only contain for example ticket numbers. The resulting printing speed is subsequently much faster, than if all data were processed for each sheet again and again.
Separate export is only available if numbering is used and this numbering is placed above the pages for imposition (option "Background" is not activated). One PDF containing background can be generated in this case (i.e. pages for imposition, marks and custom marks with the option "Background" activated) and another PDF containing variable data - numbering and custom marks placed above the pages for imposition. Only the first sheet of the imposition will be exported as a background even if the second or other sheet contains different pages for imposition. PDF containing variable data (numbering) will be exported for all sheets if the imposition. It is possible to chose if both PDF will be exported or only the background or variable one.
If you want to export pages for imposition together with variable data (numbering) in a single PDF use option Export PDF.