Abstract: A computer has a monitor and a processor. An interface system has a plurality of target data sets, at least one relation data set, a display program, a selection program, and an application program. In the plurality of target data sets, each target data set has an ID (identification) of a target. In the relation data sets, each relation data set has two IDs of two corresponding targets and a relation attribute of the two targets. The display program is used to display the plurality of target data sets and the relation data sets on the monitor in a relation graph format. Each target data set is displayed as an icon in the relation graph, and each relation data set is displayed in a linking graph format between the two icons corresponding to the two targets of the relation data set. The selection program is provided for a user to select the icons displayed on the monitor. The application program can be activated by the user to provide functionality such as distribution of e-mails to the IDs of selected icons.