Lists are used to organize and render one or more data items with some
relationship to each other. With a list structure, extra information
is used to give some indication of the degree of relationship between
the items.
But this extra information is not actually stored in the document itself,
it is generated automatically when it is rendered. List structures
generate two blocks for each item of rendered data - a box for each data
item, along with a separate marker box for the visual list iteration
object (such as a bullet, number, or image) that is created by the
system. The list properties control the type and placement of the marker
box in list contexts.