Overview

The Calculation Chain part specifies the order in which cells in the workbook were last calculated. It only records information about cells containing formulas. It does not include any information about the formula-dependency calculation tree. In other words, the Calculation Chain part does not indicate the dependencies that formulas have on other cell values; it only indicates the order in which the cells were last calculated.

Any particular calculation event can cause the calculation chain order to be rearranged or altered. For example, adding more formulas to the workbook will add references in the Calculation Chain part.

Another example of how the calculation order can be updated involves the idea of partial calculation. Partial calculation is an optimization a spreadsheet application can implement to calculate only those cells that are dependent on other cells whose values have changed, and to ignore other formulas in the workbook. This helps to avoid redundantly recalculating results that are already known. Therefore, if a set of formulas that were previously ignored during a calculation become required for calculation (due to a cell's value changing), then these formulas will move to "first" on the calculation chain so they can be evaluated.

While calculation chain information can be loaded by a spreadsheet application, it is not required. A calculation chain can be constructed in memory at load-time based on the formulas and their interdependence, if the spreadsheet application finds this information useful. The order expressed in the Calculation Chain part does not force or dictate to the implementing application the order in which calculations must be performed at runtime.