(a.) Proper to be added; positive; -- opposed to subtractive.

accession accessory accompaniment accumulative addenda addendum additament addition additional additory additum adjunct adjuvant annex annexation appanage appendage appendant appurtenance appurtenant attachment augment augmentation chain coda complement component concomitant constituent continuation corollary cumulative elemental extension extrapolation fixture increase increment offshoot pendant reinforcement side effect side issue summational summative supplement tailpiece undergirding