The article presents a model for annotating textual variants. The annotations made can be queried in order to analyse and find patterns in textual variation. The model is flexible, allowing scholars to set the boundaries of the readings, to nest or concatenate variation sites, and to annotate each pair of readings; furthermore, it organizes the characteristics of the variants in features of the readings and features of the variation. After presenting the conceptual model and its applications in a number of case studies, this article introduces two implementations in logical models: namely, a relational database schema and an OWL 2 ontology. While the scope of this article is a specific issue in textual criticism, its broader focus is on how data is structured and visualized in digital scholarly editing.