This paper describes the general architecture of a digital research environment for manuscript and textual studies (particularly those pertaining to ancient Greek and Byzantine texts), and it discusses some questions of data representation and encoding in the framework of such an online research platform. The platform is being developed by the project Teuchos. Zentrum für Handschriften- und Textforschung, established in 2007 by the Institut für Griechische und Lateinische Philologie (Universität Hamburg) in cooperation with the Aristoteles-Archiv (Freie Universität Berlin). Teuchos is a long-term infrastructural project of the Universität Hamburg. It is currently in its three-year initial phase which is being co-funded by the German Research Foundation (DFG) through the "Thematic Information Networks" scheme within the "Scientific Library Services and Information Systems" programme. We introduce the main object types to be handled by our system and describe the overall functionality of the online platform. The paper focuses on the representations of two main object types: manuscripts as textual witnesses and watermarks, with an emphasis on the former. Since the adequate encoding of different layers of structure of a transmitted text is particularly relevant to optimising users' choices of navigating both digital images of the containing manuscripts and trancriptions of the text contained, this topic is discussed in some detail. We introduce the formal data model and the corresponding encoding for the object types discussed. The project encodes textual data in XML, aiming for TEI conformance where possible. Since no accepted XML model exists for the encoding of metadata within a watermark collection, we briefly explain how we chose to model the objects to accomodate the collections the project is making accessible
