n

    Twice the value of the character position that you want to center
    the text around. (Absolute character positions on a line always
    start with 0 at the leftmost position on the page.)

    If you center the line of text between settings of the left and
    right margins, then n is equal to the value specified by the most
    recent .LEFT MARGIN command added to the value specified by the
    most recent .RIGHT MARGIN command.

 +n

    Moves the character position around which the text is centered to
    the right by n/2 character positions. This value normally is used
    to adapt .CENTER to a new setting specified by the .LEFT MARGIN
    command.

 -n

    Moves the character position around which the text is centered to
    the left by n/2 character positions. This value normally is used
    to adapt .CENTER to a new setting specified by the .RIGHT MARGIN
    command.

 text

    The text you want to center. You must enter this text on one
    line.