In the blocksworld domain, the diagram is used to visually represent the state of blocks and the hand. Each object in the diagram is encoded using specific shapes, colors, sizes, and positions, each with a distinct meaning:

1. Shapes:
   - **Rectangle**: Represents a block. All blocks are shown as rectangles to indicate their uniform shape.
   - **Large Rectangle**: Represents the table, which supports all blocks. It is placed at the bottom of the diagram to signify its foundational role.
   - **Oval**: Represents the hand. The oval shape distinguishes it from blocks and the table, indicating its unique function.

2. Colors:
   - **Green**: Indicates a "clear" status. A block is clear if there are no other blocks on top of it.
   - **Red**: Indicates a "not clear" status. A block is not clear if there is another block on top of it.

3. Sizes:
   - **Medium Rectangle**: Used for all blocks to show they are of equal size.
   - **Large Rectangle**: Used for the table to show its size relative to the blocks, covering all of them.
   - **Small Oval**: Used for the hand to indicate it is separate and smaller than the blocks and table.

4. Positions:
   - **On Table**: Blocks positioned directly on the table are placed at the bottom of the diagram, above the table.
   - **On Another Block**: Blocks positioned on another block are placed above the block they are on, maintaining a vertical stack.
   - **Above All**: The hand is positioned above all blocks to indicate its potential to interact with any block.

5. Text and Status:
   - Each object has a text label indicating its identifier (e.g., block_a) and a status label (e.g., "clear" or "supports another block").
   - The text is placed inside the shape of the object to ensure clarity and association with the object it describes.

6. Legend:
   - A legend is included to map colors to statuses. It is placed outside the main diagram area to avoid overlap with objects.

This encoding allows anyone to understand the state of the blocks and the hand by observing the shapes, colors, and positions in the diagram.