A BOX can be drawn in a graphic object. It is drawn in the current Color and the current Size. One corner is at the current pen position. The other corner's X,Y coordinates are fed to the BOX command.

#handle BOX(x, y) - Draw a box from the current position to x, y

Here is a demo that creates a graphic object, draws a box, then causes the graphic to be displayed on the web page.

'create a graphic object
graphic #g, 300, 300
'place the drawing pen at 10,10
#g place(10,10)
'draw a box
#g box(290, 290)
'add graphic to web page
render #g