Hi,
As you know, there is a small amount of info in German - from what I understand, the DDM14, whilst aimed at the ZM1200, will happily drive pretty much any group of up to 14 "normal" nixies.
It seems to be a shifted in bitstream + latch, nothing unusual, but only drives 0-9, i.e. has no decimal point support.
This is an interesting idea - the ZM1200 is a great tube, really designed for calculators - 14 digits are quite a lot.... I find the ZM1206 at 8 digits a bit more useful ("dd-mm-yy" or "hh.mm.ss" fit nicely).
NIck