| `structDir` | string | Absolute or relative path to the canonical ProjectStructure directory. Blank values default to the folder containing `config.json`. |
| `projectsRoot` | string (optional) | Override for the root directory scanned by `UpgradeSeqBatches.ps1`. Defaults to the parent of `structDir`. |
| `zipper` | bool | `true` → use 7‑Zip (if available); `false` → use Python’s built-in zipfile module. |
| `compression` | int | Compression level `0-9` (0 = store only, 9 = max). Applies to both zipfile and 7‑Zip. |