a. APUPA stands for Alien-Penumbral-Umbral-Penumbral-Alienb. In this pattern, one arranges the most relevant documents at the centre, provides documents of marginal relevance on both sides of relevant documents, and totally disconnected documents are far from the center.c. On the basis of APUPA, a subject gets placed in the classification schemed. This is the best way to maintain filiatory sequencee. APUPA arrangement diagramf. Example . . .