Interpolation tables are used where the relationship between two or three quantities may be represented by monotonically increasing piecewise linear curves. Representative points on each of the curves are entered into the rows of the table. (The easiest way to do this is to keep the data in a spreadsheet as two or three columns and then paste it into the interpolation table when constructing a model.)

The simulator uses these tables internally for reservoir area capacity relationships as shown in the figure, for tailwater discharge relationships and for hydropower.

Most interpolation tables permit multiple pages. This makes the table three dimensional. The key value (Year in the figure above) is the entry point to each page. Since the example is an area capacity table and the key is years, this table might be used to represent the change in capacity due to siltation in a reservoir. To do this, create pages in the table at several time points, each representing the reservoir capacity (either historical or forecast) at that year. The simulation engine will linearly interpolate in three dimensions based on the simulation time clock.

These tables are also useful for quick data look up. If a value is typed into the open box at the top of one column, the corresponding interpolated values are calculated and entered into the other two. To use this feature, type the known value over the appropriate column and press Enter on your keyboard. The other column(s) will be updated appropriately.

When a table is open and selected, there will be a Pages menu visible. Just select Add Page from that menu and a small dialog will pop up requesting to know the key value for that page. Enter the appropriate value and click OK. The table will go blank as the new page is added and displayed in the table. Enter values into the table either by pasting from a spreadsheet (recommended) or by typing them in.

Selecting a different key in the combo box at the top of the dialog will expose the page corresponding to that key. The page may be edited when it is exposed.