One of the harder things to do in Adobe InDesign, surprisingly for a page layout tool, is to create multilevel or outline format numbered lists. The right way to accomplish this, according to the folks at Adobe, is to create a Style for every level of the list you’d like to have! Here are Adobe’s instructions on how to do so (This content is taken directly from https://helpx.adobe.com/indesign/using/bullets-numbering.html#create_multi_level_lists):
Create multi-level lists
A multi-level list is a list that describes hierarchical relationships between the list paragraphs. These lists are also called outline lists because they resemble outlines. The list’s numbering scheme (as well as indentations) show rank as well as how items are subordinate to one another. You can tell where each paragraph fits in the list with respect to the paragraphs before and after it. You can include up to nine levels in a multi-level list.
To create a multi-level list, define the list and then create a paragraph style for each level you want. For example, a list with four levels requires four paragraph styles (each one assigned the same defined list). As you create each style, you define its numbering format and paragraph formatting.
- Choose New Paragraph Style from the Paragraph Styles panel menu.
- Enter a style name.
- If you already created a style for your multi-level list, choose the style you will assign to levels above this one from the Based On menu; otherwise, choose No Paragraph Style or Basic Paragraph.
- On the left side of the New Paragraph Style dialog box, click Bullets And Numbering.
- Choose Numbers from the List Type menu.
- Choose a list you defined from the List menu. If you haven’t yet defined your list, you can choose New List from the menu and define it now.
- In the Level box, enter a number that describes which level of the multi-level list you’re creating a style for.
- From the Format menu, choose the type of numbering you want to use.
- In the Number box, enter metacharacters or select metacharacters from the menus to describe the number formatting you want for list items at this level.
- To include numbering prefixes from higher levels, enter text or click at the start of the Number box and choose Insert Number Placeholder and then select a Level option (for example, Level 1), or enter ^ and then the list level (for example, enter ^1). In a list with first levels numbered 1, 2, 3, and so on, and second levels numbered a, b, c, and so on, including the first-level prefix in the second level renders second-level numbers as 1a, 1b, 1c; 2a, 2b, 2c; 3a, 3b, 3c.
- To create a number expression, enter punctuation, enter metacharacters, or select options on the Insert Special Character list.
- Select Restart Numbers At This Level After to renumber beginning at 1 when a paragraph at this level appears after a paragraph at a higher level; deselect this option to number paragraphs at this level consecutively throughout the list without regard for where the paragraphs appear in the list hierarchy.
To restart numbers after a specific level or range of levels, type the level number or range (such as 2-4) in the Restart Numbers At This Level After field.
- In the Bullet or Number Position area, choose Indent or Tab Position options to indent list items at this level farther than list items at higher levels. Indenting helps subordinate items in lists stand out.
- Click OK.
In some cases, such as with numbered steps, you may want to restart numbering within the same story. To avoid restarting the numbered list manually, create a separate style that’s identical to the Level 1 style with one exception. For Mode, chose Start At, and then specify 1. Name this style something like “Level 1 Restart.”
Note that Bob Bringhurst (the lead writer for the Digital Publishing Suite) provides a much more complete series of articles about using bullets and numbering to create outlines, multi-level lists, figure captions, and numbered steps.