PortMonitor

PortMonitor = display-name, filename

Specifies a port monitor that supports the installed printer model.

display-name A user-displayable, descriptive name for the port monitor. This string may not contain commas.
filename Names a DLL that is the print monitor that supports the printer model installed by the Install section of the INF file.

If no PortMonitor statement is used in the Install section or a Data section it refers to, then the default port monitor installed as part of Windows 95 is used to support the installed printer. (The default port monitor is part of SPOOLSS.DLL.)

It is a good idea to put the display-name string in the [Strings] section of the INF file, along with all the other strings that may be displayed to the user, in case displayable strings have to be translated for international markets.