PosDup is an abbreviation for "possible duplicate." PosDup sections are used to prevent more than one installation of your modem. An example PosDup section from an INF file is
[Modem12.PosDup]
*PNP0500
In this example, "Modem12" refers to the name of a modem in the Install section of the INF and "*PNP0500" refers to the node of the devnode tree for the serial port. This example PosDup section instructs the Windows 95 device installer to perform an extra step when it is running the script in the Install section of your INF file. When it encounters the Install section item that installs Modem12, the installer checks the serial port node of the devnode tree to see if that modem is currently installed. If it is, the installer deletes the existing devnode and runs the rest of the Modem12 Install section script to rebuild the devnode. This prevents a duplicate installation.
Examples usages of PosDup sections in modem INF files are shown in the following. To see other examples, search all existing Windows 95 INF files for "PosDup."