XForms: Setting default value of a field from an existing Obs

Hi all,

We have two forms(xforms) ie. a baseline and a followup form. We require some fields in the followup form to be initialized with values from the baseline form. In other words, we want the initial value of a specific field in a different form(encounter type) to be initialised with a value from some existing Obs. How can this be achieved when using the xforms technology?

(Something the <lookup/> HFE tag would do)

cc: @dkayiwa