Semilattice is a concept.

  1. A block is the basic element.
  2. Blocks attach to each other and form a list.
  3. A card consists of multiple lists of blocks and hand drawings.
  4. A card could have multiple parents and children. Locations are represented in familiar nested structure, but become relational and flexible.
  5. A designated space is within reach for quick access.

Like Notion.