One way to define a box is by specifying its size and location on the command line. The parameters nr and nc define the number of rows and columns in the box, respectively. The location can be specified either by defining the starting row and column (sr and sc) or the center row and column (cr and cc). Changing the number of rows and columns does not change the center location of the box.
The int switch allows you to define a box interactively on the image of a previous tv command. Move the cursor to an image and, if necessary, wait for the cursor to become the special "box center" shape: a small dot inside a square. Press and hold down the Left button to define the center of the box. Then, while still holding down the Left button, move the cursor to one corner of the desired box position; a rubber box will show the shape and size of the box being defined as you move the cursor. When it looks correct, release the Left button. The box center coordinates and number of rows and columns will be printed to the screen, and the box inserted into the box list. of the corners. After you have finished making a box interactively, it is displayed on all windows into which it will fit. If no box number is specified, an new box will be assigned.
The show switch presents the specified box on all displayed windows into which it can fit. If no box is specified all boxes are shown.
The del switch deletes the given box from the list of boxes. However, it will not undraw the box from any windows in which it is currently being shown.
If no arguments are specified the defined boxes are listed.
box 1 nr=10 nc=10 cc=100 cr=50-defines a box with 10 rows and columns centered on (50,100).
box 1 cc=110 show - sets the center column
of box 1 (which must already be defined) to 110 and shows it on the active tv
box 10 del - removes box 10