Workstation Customizing Objects (WSCTs) can be thought of as printer drivers that control how your spooled file is converted into commands (usually PCL) and sent to your printer. In this video, we show how to retrieve the source of a printer MFRTYPMDL (here HP4 is used as an example) into a QTXTSRC object which can be edited to create a new WSCST object. This video in particular shows how to force a printer to always send down a certain drawer value, but WSCSTs can also be created to force certain fonts, line spacings, or orientations to be used when printing occurs.
If you are using Host Print Transform (HPT) to print to a printer, you are using a WSCST already—one included with the IBM i OS and mapped to a MFRTYPMDL value that you select when configuring your printer.