A4 sizes) with an output resolution of 600 x 600 dots per inch (dpi). Scanned documents could be saved to a special memory area on disk known as the "Save Queue" where they could be retained, edited if desired (using the built in editor), and later printed "on demand". The system was also capable of printing on sheet sizes up to 14x17 inches. Another important feature of this earliest DocuTech was its ability to perform signature imposition and generate "2-up signatures" (later 4-up was added) in the proper page imposition order to create signature booklets. (note: Folding, trimming, and stitching of booklets was done by an optional accessory known as a C.P. Bourg Signature Booklet Maker or SBM-1, which could be attached in-line to the system's output finisher.) In June 1992 Xerox announced the DocuTech 135 Network Publisher which augmented the earlier DocuTech's capability by enabling it to receive and print documents transmitted over a network. Although this system's network connectivity was limited to Xerox's proprietary XNS network, a DocuTech Network Server was also offered which enabled the now growing family of DocuTech Publishing Systems to be utilized with a broader set of networks. The DocuTech 6135 is an improved version of the DT135, with a Sun Microsystems workstation controller replacing the original controller and scanner. Additional improvements include an optional VLD laser assembly, which uses sub-pixel dot positioning, while not truly increasing the print resolution to 600 x 1200 dpi, improves the halftone quality. The DocuTech system's main competitor in the field of print-on-demand production plant is IBM's InfoPrint system. In addition, there are a number of other competitors in the field, led by the Kodak Digimaster Production Printer, which is sold under a number of different brand names, including the Canon imageRUNNER and the IBM InfoPrint. Xerox retired the original DocuTech 135 platform in favor of the DocuTech 61xx and later, the Nuvera systems (originally introduced as the DocuTech 100/120 Copier/Printer). See also Xerox IBM Print on demand .rdo References Page at ieee.org on the Xerox's DocuTech system All articles with unsourced statements Xerox Digital press