This paper discusses the conceptualisation of a novel data model for analysing the account books of the Loitz, a Lower German merchant company in the sixteenth century. Departing from the database structure developed in a previous project, the paper proposes a new model that distinguishes between source-oriented and research-oriented data structures. The source-oriented data structure preserves the original content of the account books as faithfully as possible. The research-oriented data structure incorporates semantic annotations and standardizations to facilitate specific historical questions. This structure adds layers of information, such as the categorization of entries and metadata about transactions, locations, and individuals involved. The paper emphasizes the importance of both preserving the original data and enhancing it with additional information to support detailed analysis of the economic activities of the Loitz.