LOCALFORMULAEXISTS Function [Visio 2003 SDK Documentation]
Indicates whether the referenced cell contains a local formula.
LOCALFORMULAEXISTS (cellref)
cellref The cell that you want to check for the presence of a formula.
Remarks
The LOCALFORMULAEXISTS function returns 1 if the cell contains a local formula; otherwise, 0 (zero) if there is no formula or the formula is inherited.