How to apply different style heading

I want to make format like this for heading style

I BAB 

1.1 SUB BAB

1.1.1 SUB BAB

II BAB

2.1 SUB BAB

2.1.1 SUB BAB

I’m confused how to format like that.

Thanks alot

There exists no predefined way to do so, because it is a very curious style. It is very unusual, to give the number of the first level a different style, depending where the number occurs. In which context do you need such numbering?

I assume, that you are familiar with setting the numbers via Tools > Outline Numbering. You can fake the behavior, by setting “hidden” in font property tab of the paragraph style of the first heading level (usually Heading 1), and manually write a fake heading in the following line. For the number in the fake heading you can use a number range, so that it adapts automatically when moving whole chapters. In the number range definition you can choose the numbering format I,II,III. For the heading text you can use a reference to the original heading. The original heading gets the number format 1,2,3, same as all other headings. For the fake heading you define a paragraph style, which is a child of Heading 1, where you remove the check in option ‘hidden’.

The best guide I have found is odfauthors advanced-character-and-paragraph-styles
about use of list styles and outline & numbering.

Attached a sample file with it. Several heading numerations with another approach to solve the question.

Not easy arrive to it, but at the end it’s not too much complicated, after a bit of research and test. The key is the use of the Menu/Tools/Outline numbering, it’s the only place that I have found to assign automatically a level to a paragraph style.

  1. In Menu/Tools/Outline numbering.
    Select level 1 → paragraph style [None]
    Select level 1-10 → number = 1,2,3…
    Ok.

  2. Edit style Heading 1, in Outline&Numbering tab,
    select for Numbering style = Numbering 4 (Roman).

  3. For the table index, when it is created, is needed to add in:
    Create From (Index/Table tab), Additional styles, the Heading 1 style to level 1.
    It was deselected of Outline in step 1.

At least, I have learned a bit about the use of lists, a pending lesson for me.

doesn’t seems to works on v5.2.5.1 x64 on Win10.

the numbering turned to `I BAB

1.1 SUB BAB

1.1.1 SUB BAB

II BAB

1.2 SUB BAB

1.2.1 SUB BAB`