The width and height of an application window are usually measured in pixels. Some applications, however, use more meaningful measurement. For example, the dimensions of an xterm window are measured in columns and rows of font characters. The x and y offsets in geometry resources can be either positive or negative. If you specify positive values, you position the left side and top side of the window.
Negative offsets position the right side and the bottom side of the window.
The possible values for the x and y offsets and their effects are shown as follows. A positive value in xoff specifies the distance by which the left edge of the window is offset from the left side of the display. A positive value in yoff specifies the distance by which the top edge of the window is offset from the top of the display. A negative value in xoff specifies the distance by which the right edge of the window is offset from the right side of the display. A negative value in yoff specifies the distance by which the bottom edge of the window is offset from the bottom of the display.