Xerox 4890 Advanced, Troubleshooting Manual

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Optimizing print quality
5-2 Troubleshooting Guide
If a PQA command is issued on an NPS/IPS system with a
bypass transport installed, the trailing sheet is sent to the bypass
transport, but the test patterns are not.
Example Manually running a PQA
Product features that affect PostScript print quality
You can improve the appearance of your documents by being
aware of potential problems created through the use of
proprietary PostScript extensions and device-dependent
operators.
Proprietary PostScript extensions
PostScript masters that use proprietary printer features may
cause appearance inconsistencies between different PostScript
printers. Some PostScript printers contain proprietary PostScript
extensions. For example, some versions of the Apple Macintosh
PostScript driver download encrypted proprietary image
“smoothing” operators to Apple LaserWriters. The downloaded
PostScript code uses the product operator to determine if it is
being used on a LaserWriter. If not, the proprietary code is
bypassed by doing a flushfile. This allows the PostScript master
to print on non–LaserWriter products. As a result, PostScript
masters generated on a Macintosh with Apple proprietary
features may produce output that varies between LaserWriter
and non–LaserWriter PostScript printers.
Access level Administrator or operator
Syntax PQA
Arguments None
PS–op> pqa
DocuPrint manual PQA submitted as document number: (N)