If you do not specify a value for any given n, DSR supplies the
    following default values:

    n1=3  Run-in titles for header levels 3 to 6.
    n2=1  Titles in all uppercase for header level 1 only.
    n3=6  Titles with only the first letter of every word in
          uppercase for header level 2 to header level 6.
    n4=7  A sequence of numbers (or letters) preceding the section
          title. (See .DISPLAY LEVELS.)
    n5=7  Titles printed starting at the left margin (flush left),
          not centered.
    n6=3  Three blank lines before each header.
    n7=1  One blank line after each header.
    n8=9  Seven more than the test-page value of the most recent
          .PARAGRAPH or .SET PARAGRAPH command you have entered. If
          you have not specified such a value, you get 7 plus the
          .PARAGRAPH default of 2. (See the description of n8 for
          note on .SPACING adjustment.)
    n9=2  Two spaces between the section number of the header and the
          header itself (section title).