18.104.22.168.3 Formula Evaluation
The parse tokens that make up the formula expression are evaluated in sequence as specified by the Order of Operations. Each function token and reference token in the formula expression is evaluated to produce an operand token.
The logic for evaluating a particular function token is specified by the Function Token Definitions. A reference token is evaluated by returning the value of the cell specified by the reference token. Functions and references are evaluated within a reference context, which is the specification of the sheet containing the properties to be used in the evaluation.
When the formula expression of a cell is evaluated, the formula expressions of other cells that contain reference tokens that reference the cell are also evaluated.