The .DISPLAY LEVELS command allows you to specify the form that
    sequential numbering (or lettering) of section headers will
    take. You can control the form of individual numbers within a
    section number for a header (that is, those numbers preceding
    or following a dot). This command does not change any values; it
    affects only the way the values are displayed.(See also .HEADER
    LEVEL, .NUMBER LEVEL, and .STYLE HEADERS.)

    Default Header Level Numbering

    Command            Nonchapter  Chapter n   Appendix A

    .HEADER LEVEL 1    1           n.1         A.1
    .HEADER LEVEL 2    1.1         n.1.1       A.1.1
    .HEADER LEVEL 3    1.1.1       n.1.1.1     A.1.1.1

    Format

      .DISPLAY LEVELS  [y1] [,y2]...[,y6]

    Abreviated format

      .DHL  [y1][,y2]...[,y6]

1  –  Parameter

 y

    One of the following one- or two-letter codes; 1,2, ... 6
    indicate positions of numbers (or letters) for a section header.
    The commas correspond to the dots in a printed section number.
    (See also .NUMBER LEVEL.)

    Code  Form of Sequence and Case

    D     Decimal numbers
    O     Octal numbers
    H     Hexadecimal numbers
    RU    Roman uppercase numerals
    RL    Roman lowercase numerals
    RM    Roman mixed case numerals - only first numeral is uppercase
    LU    Letters, uppercase
    LL    Letters, lowercase
    LM    Letters, mixed case - only first letter is uppercase

2  –  Default

    Decimal numbers (D)

3  –  Example

 Entering the command .DISPLAY LEVELS RU, LU, LL (roman numeral
 upper, letters uppercase, letters lowercase) would cause your
 headers to be displayed as follows:

      Command            Nonchapter   Chapter n  Appendix A

      .HEADER LEVEL 1    I            n.I        A.I
      .HEADER LEVEL 2    I.A          n.I.A      A.I.A
      .HEADER LEVEL 3    I.A.a        n.I.A.a    A.I.A.a