Specifications

3-15
Spooler Overview
The formatter driver is invoked by a pipeline and 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 performs the necessary functions, it returns
to the formatter driver. The formatter driver calls the initialize function. The initialize
function outputs a string of printer commands to initialize the printer and returns to the
formatter driver.
The formatter driver either calls the passthru function once or calls 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, including line spacing,
vertical tabs, form feeds, and top and bottom margins. Line spacing and vertical tabs are
performed by the lineout function. Other vertical spacing functions are performed
automatically.
When processing is complete, the formatter driver calls the restore function. The restore
function outputs a string of printer commands to restore the printer to its default state,
defined by the database attribute values.
For more information about how the print formatter interacts with the printer formatter
subroutines, see the example of a print formatter ( Example of Print Formatter on page
4-26).