. "It is also a feature of the purge/clean system 22 that it includes means, generally indicated 152 in FIGS. 1 and 12, for creating a zone of above-atmospheric pressure in a region adjacent the front plate 58 of the printer head 30 of a printing system to help maintain the orifices 60 of the front plate 58 relatively clean, or in other words, free of matter, such as unwanted dust and debris, which c" . . .