This paper presents an analysis of online discussions in Open Source Software (OSS) design. The objective of our work is to understand and model the dynamics of OSS design that take place in mailing list exchanges. We show how quotation practices can be used to locate design relevant data in discussion archives. OSS developers use quotation as a mechanism to maintain the discursive context. To retrace thematic coherence in the online discussions of a major OSS project, Python, we follow how messages are linked through quotation practices. We compare our quotation-based analysis with a more conventional analysis: a thread-based of the reply-to links between messages. The advantages of a quotation-based analysis over a thread-based analysis are outlined. Our analysis reveals also the links between the social structure and elements in the discussion space and how it shapes influence in the design process.