Using the indentation properties in AL, you can display rows in a parent-child structure.
A row that’s indented from a row above is considered a child of that row. The row above is considered the parent. Indenting rows can help organize related records in the list and make it more readable for the user. You can display indented hierarchy lists on any page type, including List pages, Worksheets, and ListParts. Pages can also be editable.
There are two kinds of indented hierarchy lists: fixed and collapsible. In a fixed hierarchy, rows that are indented are always shown. In a collapsible, users can collapse and expand parent rows to show and hide child records.