schema.md

# Schema

The authoritative dataset file is `full.parquet`. It contains 3,887 rows and 21 columns.

| Column | Type | Description |
| --- | --- | --- |
| `id` | string | Stable item identifier. |
| `year` | string | Competition year. |
| `group` | string | Grade bucket: `3-4`, `5-6`, `7-8`, `9-10`, or `11-13`. |
| `language` | string | Item language; currently `de`. |
| `points` | int32 | Official item value: 3, 4, or 5. |
| `problem_number` | string | Problem number within the exam. |
| `problem_statement` | string | OCR-corrected problem statement text. |
| `answer` | string | Gold multiple-choice answer label: `A`, `B`, `C`, `D`, or `E`. |
| `multimodal` | bool | Whether the item contains a question image or image-based answer option. |
| `sol_A` | string/null | Text for answer option A when available. |
| `sol_B` | string/null | Text for answer option B when available. |
| `sol_C` | string/null | Text for answer option C when available. |
| `sol_D` | string/null | Text for answer option D when available. |
| `sol_E` | string/null | Text for answer option E when available. |
| `question_image` | bytes/null | PNG bytes for the question crop or visual stem. |
| `sol_A_image_bin` | bytes/null | PNG bytes for graphical answer option A. |
| `sol_B_image_bin` | bytes/null | PNG bytes for graphical answer option B. |
| `sol_C_image_bin` | bytes/null | PNG bytes for graphical answer option C. |
| `sol_D_image_bin` | bytes/null | PNG bytes for graphical answer option D. |
| `sol_E_image_bin` | bytes/null | PNG bytes for graphical answer option E. |
| `associated_images_bin` | list | Additional associated PNG image payloads where applicable. |

Image fields are stored directly as binary payloads. Text answer fields may be null when the corresponding answer option is graphical.