Filtering a Picklist

Hi,

I want to be able to filter a picklist based on a field on the same form as the picklist. If I use the example below:

form FormB

values = FormA[Country == "India"].State

Instead of using the variable string "India", I want to be able to refer to a field on FormB called [Country]. What would be the syntex?

Thanks,
Martyn
martynhale