Will two combined PDF/X-3's retain the X-3 format?

[Stewart Noy]

Hi,
I am using Scribus to create a book but it doesn't handle very long docs, so I am splitting it into 5 seperate PDF's that will be combined.

These will be in PDF/X-3 format (my printer would prefer X-1a but Scribus so far only does 1.3, 1.4, 1.5 and X-3), and I will combine the five into one using PDFtk.

So my newbie question is: once I start merging the PDF's, will the resultant combined PDF retain the X-3 charactaristics of the originals?

Cheers

Stewart