In the Tetris domain visualization, each object type and its attributes are encoded using specific visual elements to convey their properties and status clearly. Here's how each aspect is represented:

1. **Shapes and Sizes:**
   - **One-Square Piece:** Represented by a single square. It occupies one grid cell, and all its edges are bold to indicate its boundaries clearly.
   - **Two-Square Straight Piece:** Represented by two connected squares in a straight line. The outer edges of the combined shape are bold to distinguish the piece's boundary.
   - **Right-L Piece:** Represented by three connected squares forming an "L" shape. The outer edges of the "L" are bold to highlight its boundary, while the internal lines remain standard.
   - **Grid Cells:** Each unoccupied grid cell is depicted as a single square with standard (non-bold) edges.

2. **Colors:**
   - Each piece type is assigned a distinct color to differentiate between them:
     - **One-Square Piece:** Red or Yellow, indicating different instances.
     - **Two-Square Straight Piece:** A unique color (not used in this instance).
     - **Right-L Piece:** Blue or Green, indicating different instances.
   - **Grid Cells:** Clear cells are left colorless or given a light color to indicate availability for movement.

3. **Text Labels and Status:**
   - Each piece and grid cell is labeled with its identifier and status. The text is positioned within the shape, slightly adjusted vertically to avoid overlap.
   - **Statuses:** 
     - For pieces, the status is "Occupied."
     - For grid cells, the status is "Clear."
   - Text colors are chosen to contrast with the background for readability.

4. **Legend:**
   - A legend is included to map each color to its corresponding piece type or status. This ensures that the viewer can easily understand the diagram without prior knowledge of the color coding.

5. **Positioning:**
   - The grid is organized in rows and columns, with each piece placed according to its specified positions. This spatial arrangement reflects the logical structure of the Tetris grid.

By adhering to these visual conventions, the diagram effectively communicates the initial state of the Tetris puzzle, allowing viewers to comprehend the arrangement and status of each piece and grid cell.