# File lib/ruote/exp/ro_variables.rb, line 238
    def set_vf(key, value, opts={})

      field, key = if m = PREFIX_REGEX.match(key)
        [ F_PREFIX_REGEX.match(m[1]), m[2] ]
      else
        [ true, key ]
      end

      field ? set_f(key, value, opts) : set_v(key, value, opts)
    end