Syntax:        TXDOTVLINE(<expN1>,<expN2>,<expN3>,<expN4>)

     Purpose:       Prints a vertical line at the designated x and y
                    coordinates with a height of <expN3> and <expN4>
                    dots wide. TXDOTVLINE() allows you to draw a
                    vertical line with great control over the line
                    placement.

     Arguments:     <expN1> is the x coordinate of text to be printed.

                    <expN2> is the y coordinate of text to be printed.

                    <expN3> is the height of your line in dots. 300
                    dots equal 1 inch.

                    <expN4> is the weight of the line. (Number of dots
                    wide). 300 dots equal 1 inch.

     Returns:        0  Successful
                     1  Invalid number of parameters
                     2  <expN1> x parameter not numeric
                     3  <expN2> y parameter not numeric
                     4  <expN3> length parameter not numeric
                     5  <expN4> weight parameter not numeric

     Usage:         TXDOTVLINE() is useful anytime you need to draw an
                    exact vertical line of any weight (width).
                    TXDOTVLINE() is much more exact than TXCOLVLINE()
                    and requires calculating your exact print
                    position. 300 dots equal 1 inch.

     Example:       * To print grid on a page.
                    for i = 1 to 2400 step 75
                       TXDOTVLINE( i, 01, 3300, 1)
                    next

                    for i = 1 to 3000 step 75
                       TXDOTHLINE(01, i, 2400, 1)
                    next

     See Also:      TXDOTHLINE(), TXCOLVLINE(), TXCOLHLINE()