Hugo Etherianus, De sancto et immortali Deo

The RAP online database offers the first comprehensive catalogue of polemical literature related to the schism between the Roman Catholic and Orthodox Churches from the 9th to the 16th century and can be described as an ideal continuation of the *Clavis Patrum*. Each entry identifies the work (often unpublished or newly discovered in manuscript catalogs), lists its various titles (since medieval texts often lack stable titles), provides incipit and explicit (with possible variations), and examines the manuscript tradition and foliation (by reviewing catalogs or manuscripts, verifying dates, folios, etc.). It also includes relevant bibliography (critical editions and studies), identifies the author (using prosopographical studies, dictionaries, repertories, sigillography, etc.), and provides essential biographical details. Each work is classified by literary genre (e.g., treatise, dialogue), the corresponding Byzantine term, and the main polemical themes (e.g., Filioque, Azymes, Purgatory), and is assigned a unique RAP identification number.