If the user clicks on the body area of a device defined with a Device block in the technology file, an extraction is performed and the results are printed. The format of the output is defined in the Device block following the Cmput keyword. The !find command can be used to highlight extractable devices in the physical layout.
If the user drags, or presses and holds, the behavior of the command is different. A ghost rectangle is shown, and the per-square parameter from the current layer adjusted for the rectangle aspect ratio is printed when the user releases button 1 or clicks a second time (thus completing the rectangle). The electrical specifications are given in the technology file, and may be edited with the Edit Extraction command. The Compute Params command is especially useful when creating devices such as resistors. It is also useful for extracting electrical parameters from existing layouts.
These results can also be shown when the user creates a box with the boxes (side menu) command on a layer with electrical parameters specified.