A 20m square is divided into 40 by 40 0.5m quadrats. Observations are in tens of grams of herb remains, 0 being from 0g to less than 10g, and so on. Analysis was mostly conducted using the interior 32 by 32 grid.
Source
Upton, G., Fingleton, B. 1985 Spatial data analysis by example: point pattern and quatitative data, Wiley, pp. 38–39.