What is the general notation for supporting points in an outline?

In an outline, supporting points are typically denoted using a combination of numbers and letters. Main ideas are often labeled with Roman numerals (I, II, III), while supporting points under each main idea may use capital letters (A, B, C). Further subdivisions can be indicated with Arabic numerals (1, 2, 3) and lowercase letters (a, b, c). This hierarchical structure helps organize the information clearly.