This document discusses the Calculation Chain metadata that Excel saves to the workbook.
What is the Calculation Chain?
Excel formulas can reference the result of other formulas. This is a powerful concept that allows formulas to build on the outcome of other formulas, which is core to spreadsheeting. To optimally calculate the formulas in a workbook, Excel creates and maintains a data structure that tracks the calculation order of all formulas in the workbook; this is the Calculation Chain.
Why is the Calculation Chain saved to the workbook?
It may take multiple edits and calculations for the Calculation Chain to settle into an optimized state. A Calculation Chain is in an optimized state when Excel can calculate formulas in the workbook without having to reorder the Calculation Chain.
To improve performance, Excel saves out the current state of the Calculation Chain which specifies the last calculation order of formulas in the workbook, so it does not need to start from scratch on every file load.
How does the Calculation Chain state relate to the workbook?
The Calculation Chain is a dynamic structure, which may be reordered when the workbook is edited or calculated. For any given workbook, there may be multiple valid Calculation Chains. And for every Calculation Chain, there could be various combinations of workbook edits or calculations that could generate that Calculation Chain.
