DSR routinely inserts an extra expandable space after a period
    (.), colon (:), question mark (?), or exclamation point (!) that
    is followed by the usual end-of-word space.

    The Period flag (+) lets you specify the extra space following
    other characters.

    If the flag is turned on and .FILL is in effect, an extra
    space occurs when the flag (+) is inserted directly after the
    character. You must, however, insert the end-of-word space after
    the flag if it is to be effective.

    For example, if you have a complete sentence enclosed in
    quotation marks or parentheses, you may want an extra space after
    the closing quotation mark or parenthesis.