The cursor routine

GR_CURS (XU,YU,X4,Y4,CODE)

Calls the interactive graphic cursor and returns its position when you hit any alphanumeric key on the keyboard.

Arguments :
        XU      REAL*8       X User coordinates    Output
        YU      REAL*8       Y User coordinates    Output
        X4      REAL*4       X Plot coordinates    Output
        Y4      REAL*4       Y Plot coordinates    Output
        CODE    CHARACTER*1  Character struck      Output

The subroutine returns CODE = 'E' when an error occurs.

For X-Window terminals, button 1 returns ^ , 2 returns & and 3 returns $*$.