The difference cells relate to the supply cells to the left. The figure can be positive, negative or zero. The difference is calculated as the difference between the supply to the left of it at the given time snapshot and the supply column below it. In other words, how much the supply has gone up or down in that time period. On page 1, the top difference cell shows the difference during the currrent time period and the previous one. This row is higlighted to show this is ongoing. Other columns show a snapshot of data taken at the given day and time in the far left column. All times shown are GMT (Greenwich Mean Time). To highlight rows just tap or click on the row(s) to cycle background colours.