Fantasia - Spool File Processing
The software supports facilities for the automatic pick-up and
formatting of spooled printer output from existing applications.
For example printer files normally associated with pre-printed
forms can have a FANTASIA form applied and be rerouted to a laser
printer simply by configuring that the named file should be
processed by FANTASIA before printing (FANTASIA can scan the output
spool queue for such files and intercept them).
Other examples of using this capability are for printing all
$STDLISTS in a small font in 2-up format to save paper, or applying
a style/environment file to all documents with a certain name.