To manage formulas, PRD implements the open standard OpenFormula. According to OpenFormula's specifications:
"OpenFormula is an open format for exchanging recalculated formulas between office application implementations, particularly for spreadsheets. OpenFormula defines the types, syntax, and semantics for calculated formulas, including many predefined functions and operations, so that formulas can be exchanged between applications and produce substantively equal outputs when recalculated with equal inputs. Both closed and open source software can implement OpenFormula."
For more information on OpenFormula, refer to the following links: