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HP OpenVMS Systemsask the wizard |
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The Question is: Can escape and control codes be generated directly from OpenVMS to an HP printer? And if so, how? Thanks, Wiz. The Answer is : Escape and control codes are simply characters, and characters can be sent to printers. The question then becomes one of interpretation and printer state, as most printers have constraints on the expected file and data stream contents -- what you need to do depends greatly on what you want to do, and on which printer is involved. If you wish a particular action on a target device (eg: bold, etc) rather than a particular character or character sequence, you can retrieve various associated character sequences from SMG using (or potentially extending) its existing dictionary contents and capabilities. See the SMG$GET_TERM_DATA, and the SMG terminal device data file. Directly embeding sequences within applications tends to cause problems when devices change or additional devices are added, as specific devices can have specific requirements in this area. That said, most folks will use an application or particularly a print file format (eg: Postscript) which will effectively locate and embed the appropriate sequence(s) into the data stream for the particular target device -- use of Postscript-format files, for instance, avoids having to code device-specific knowledge into the application. Again, most folks will prefer to avoid embedding escape or control sequences directly into the file or directly into the printer data stream. For details on device control libraries, please see existing printing discussions here starting with (1020). If you inject characters directly in the data stream, you will have to be familiar with the character set and command requirements of the printer. (eg: with the PCL language for many printers, or with Postscript for printers or hosts with Postscript printing support.) For details on generating Postscript output directly from within an application, please see the Postscript "Red Book" or other such documentation. Related topics: (7715), (102), (436), (2840), (3795), (4641), (5968). Also please see the information on escape and control sequences in the OpenVMS Frequently Asked Questions (FAQ).
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