The booktype is only recorded on the media when you burn the disc.
Pioneer burners automatically booktype DVD+R DL media to DVD-ROM by themselves (no software command/action required), so you don't need to worry about it
Ok thanks everybody, just for the science I confirm: Pioneer sets DVDROM automatically.
NOw I have a different problem and need to understand why the H. the burned iso is not working, but this is my problem, I think.
Thanks again everybody for the nice support.