You enter the path of a directory and a file pattern (*.rpm) and linuxconf will find out the list of packages in this directory that are different from the currently installed packages on your computer.
The directory field has a help list which is set with the various directory entered in the preference dialog.
Three check-boxes let you control the selection. Those check-boxes may be used in combination.
Managerpm only shows package version newer than the one installed on your workstation. Sometime, update directories contains older version when the vendor finds out that downgrading is better (because the current version is known to be too buggy or have a security flaw).
A check-box expands the view, showing older version of the packages.
By default, managerpm only presents the package candidate for update: They are already installed on your system and a newer version is available in the directory. A check-box lets you expand the view by showing packages which are not currently installed.
Normally, only the newest version of a package is presented. Managerpm silently remove from the list the older version. This check-box will disable this behavior. One will normally use that when he is unsure if he wants to upgrade to the newest (and potentially buggy) version.