DEPENDSON Function [Visio 2003 SDK Documentation]
Creates a cell reference dependency.
DEPENDSON(cellref[,cellref2,...])
Remarks
This function always returns FALSE. It has no effect when used in an Event row or an Action cell.
Example
OPENTEXTWIN() + DEPENDSON(PinX,PinY)
Opens the text block for a shape whenever the shape's PinX or PinY cells change.