One way to limit arguments to only the minimal text needed for a given discourse relation (a minimality principle), was to allow annotators to specify that other text appeared relevant but not necessary to that interpretation.
they could annotate as Sup1, material supplementary to Arg1, as in Example 17, where the preceding question was annotated as relevant to interpreting the question response particle, and as Sup2, material supplementary to Arg2, as in Example 18, where the material enclosed in square brackets was annotated as relevant but not necessary to interpreting the temporal relation expressed with then.