Content is rendered by vertically stacking all the Blocks.
Hierarchy
Header Blocks are rendered with larger bold text, and nested Headers should be smaller to help the reader visually understand the structure of the Content.
Children Blocks are generally indented, unless they appear within a Header block. Under a Header, the hierarchy should be visually apparent without using blank horizontal space to indicate it.
Collapsing
Clients should support the ability for a reader to Collapse, hiding all children of a Block Node. This will help the reader hide content they are not interested in, or aren't ready to read yet.