| Filtration Method Code | Description |
| 1 | original values are volumetric (filtvol not provided) |
| 2 | as-provided (via originators flow meter) |
| 3 | as-provided (calculated/unspecified method) |
| 4 | as-provided (loose originators estimate) |
| 5 | COPEPOD calculated |
| 6 | COPEPOD calculated |