Returns the ASCII value or color attribute of a character at a specified
screen location.
 
SCREEN (row%,column% [,colorflag%])
 
    - row%          The row coordinate of a character.
    - column%       The column coordinate of a character.
    - colorflag%    A value (0 or 1) that specifies what is returned.
 
                    Value             Returns
                    --------------    --------------------------------
                    0 (or omitted)    The character's ASCII code.
                    1                 The character's color attribute.
 
Example:
    CLS
    PRINT "Hello"
    PRINT "The ASCII value of character at 1,1 is"; SCREEN(1, 1)
 
See Also    <POINT>    <SCREEN STATEMENT>
            <ASCII CHARACTER CODES>    <COLOR ATTRIBUTES AND VALUES>