Specifications

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Guide to Printers and Printing
Printing terminology
The following list defines terms commonly used with printing.
formatter filter
Provides the capability of either formatting the input print file or passing it
through unmodified, based on an input parameter. Even if the filter passes
the input file unmodified, it still sends printer commands to initialize the
printer before the input file is printed and restores the printer after printing is
complete.
The formatter filter is made up of the following components:
– A device–independent formatter driver
– A device–dependent formatter
There is a formatter for each type (or group of types) of input data. For example,
there is one formatter for all the supported IBM Proprinters.
Invoked by a pipeline, the formatter driver is passed the name of a formatter to be
driven. The formatter driver dynamically loads and links the formatter and calls the
formatter’s setup function, which indicates whether data formatting or data
pass–through is requested. After the formatter’s setup function prepares the input file
to be modified or passed through, it returns to the formatter driver. The formatter
driver then calls the initialize function, which outputs a string of printer commands
that starts the printer.
The formatter driver next calls either the passthru function once or the lineout
function for each line in the print file based on the return code from the setup
function. If the lineout function is called,the formatter driver performs all vertical
spacing either automatically (form feeds, top and bottom margins) or through the
lineout function (line spacing, vertical tabs).
When processing is complete, the formatter driver calls the restore function. The
restore function outputs a string of printer commands that restore the printer to its
default state, which is defined by the database attribute values.
For more information about how the print formatter interacts with the printer formatter
subroutines, see Example of Print Formatter on page 4-26.
local printer
The printer attached to a node or host.
print job
A unit of work to be run on a printer. A print job can consist of printing one
or more files, depending on how the print job is requested. The system
assigns a unique job number to each job it prints.
print spooler
A generic spooling function that can be used for queuing various types of jobs,
including print jobs queued to a printer. The spooler does not normally distinguish the
types of jobs it is queuing. A system administrator defines a spooler queue abased on
the spooler backend program that is specified for the queue. For example, if the
spooler backend program is the piobe command (the printer I/O backend), the queue
is a print queue.
Likewise, if the spooler backend program is a compiler, the queue is for compile jobs.
When the spooler’s qdaemon process selects a job from a spooler queue, it runs the
job by calling the backend program specified by the system administrator when the
queue was defined.
When networks are composed of base operating system machines and other types of
clients and servers, not all remote print requests are supported across the network. In