Heading
Headings get style “myHeading”, “mySubheading” and “mySubsubheading”. They were set to Outline Level “Level 1”, “Level 2” and “Level 3” respectively in the properties dialog of the style.

Subheading
I have defined a numbering style “myNumbering” with A on first level, A.I on second level and (a) on third level. This numbering style is set in the paragraph properties of my heading styles in addition to the Outline Level. The UI in the properties dialog has no setting to determine the list level. All three heading styles get the same numbering style assigned. The paragraph styles were newly assigned to the headings for to make the changes appear.

Subheading
TOC is set up to use “Outline”.

Sub-Subheading
Dummy text

Sub-Subheading
Dummy Text

Heading
Dummy Test