Targets Overlay A Target is a cell where head is known. Targets are used mainly for determining calibration statistics. Head values calculated by MODFLOW in the Target cells are compared to the Target values you set. Consult the Calibration Statistics window under the Display menu for more information. The Target Overlay window includes a single text box and Set Target, Clear Target, and Finished buttons. Like Cell Stress overlays, a Target is set for only certain cells, but unlike Cell Stress overlays a cell may have only one Target. Choose a layer, select a cell or a group of cells within that layer, enter a value in the text box, then press the Set Target button. Target cells are indicated by a red inner border. If the scale is large enough (see the View menu) and the Cell Values box is checked (see the View Preferences window), the value will appear within the cell. A dot is displayed in the cell if it is too small to display the entire number. Values can be changed simply by repeating the process. Clicking on the Clear Target button removes selected cells as Targets. Targets do not effect the execution of a model and may be set either before or after a model is run.