从IValueConverter获取对ViewModel的引用

Is there a clean and/or an accepted standard way of referring back to the ViewModel from an IValueConverter, or does that break the MVVM pattern? Basically, I want to convert bound data in the UI based on other properties of the ViewModel. I guess this is the same question as how do you refer back to the Window/Page from an IValueConverter since a reference to the control is not passed to the Convert/ConvertBack methods.Is there a clean and/or an accepted standard wa