From Fragmented to Unified: A Pipe Organ Database Initiative

From Fragmented to Unified: A Pipe Organ Database Initiative Working Paper [v1] 2025 Dominik Ukolov Digital Humanities (Image/Object), Friedrich-Schiller-University Jena Research Center DIGITAL ORGANOLOGY, Leipzig University [email protected] Working Paper [v1] submitted on 19 November, 2025. DOI [v1]: 10.5281/zenodo.17643030 Abstract The pipe organ constitutes a distinct ontological challenge within organology, functioning as a complex, cumulative industrial system permanently embedded within an architectural host. Prevailing documentation frameworks, typified by the static inventory paradigms, frequently reduce the instrument to discrete attribute sets, thereby creating fragmented data silos that fail to model its non-linear historical lineage and material fluidity. This working paper delineates a transition from these document-centric paradigms to a unified, ontologydriven database architecture capable of resolving the identity paradoxes inherent in musical instrument history. Central to this initiative is the rigorous distinction between continuants (enduring juridical or conceptual identities) and manifestations (transient temporal states), implemented via a schema that prioritizes strict database-level referential integrity over application-level polymorphism. Beyond correcting the epistemic deficits of existing registers — such as the National Pipe Organ Register (NPOR) and LIDO-based systems — the proposed Transformation Ontology integrates the concept of the Virtual Acoustic Object (VAO). This architecture facilitates a multimodal research environment where historical provenance, 3D geometry, and causal acoustic simulation are synthesized into a single, interoperable semantic framework. Keywords Digitization ·Musical Instrument ·Pipe Organ ·Augmentation ·Recording ·Software Pipe Organ Database Initiative Working Paper [v1] 1 Epistemological Challenges in Digital Organology The documentation of the pipe organ presents a unique ontological crisis. While standard organology taxonomies classify instruments based on sound production (aerophones), the pipe organ defies the constraints of a discrete, portable object. It functions as a complex industrial system permanently embedded within an architectural host, possessing a lifecycle that is rarely linear. Throughout its existence, an organ acts as a cumulative archive of interventions. A single instrument may be built in the 17th century, expanded in the 19th, electrified in the 20th, and historically reconstructed in the 21st. In this process, windchests are replaced, pipework is revoiced, and entire divisions may be transferred from other, defunct instruments. Consequently, the ‘identity’ of the organ is not a fixed constant but a fluid trajectory. The fundamental limitation in current documentation is that our digital tools have not evolved to match this physical reality. We possess vast, isolated silos of data that function primarily as static censuses. They capture the specification of an instrument at a frozen moment but fail to model the continuous, non-linear lineage of the instrument’s identity [1]. This report outlines a comprehensive initiative to transition from these document-centric models to a unified, ontology-driven database architecture capable of resolving the ‘Ship of Theseus’ paradox inherent in cultural heritage. 1.1 The ‘Ship of Theseus’ Paradox in Cultural Heritage The philosophical puzzle of the Ship of Theseus asks: if a ship has all its planks replaced one by one, is it still the same ship? And if the old planks are reassembled into a new vessel, which is the ‘original’? In the domain of pipe organs, this is not a thought experiment; it is the operational challenge of the archivist. Standard databases typically handle this by creating a new record for the ‘rebuild’ or appending text notes to the original entry [2]. This approach maintains a superficial continuity but severs the deep semantic links required for computational analysis. The proposed Unified Initiative addresses this by fundamentally decoupling the identity of the organ from its constitution. By defining the Continuant as the enduring legal or conceptual entity and the Manifestation as the transient physical configuration, the database can model the Ship of Theseus not as a paradox, but as a documented series of Transformation events. 1.2 The Imperative for Database-Level Integrity A central tenet of this initiative is the rejection of ‘application-level’ integrity in favor of ‘database-level’ integrity. In many modern web development frameworks, data relationships are managed by the application software (e.g., polymorphic associations), where a single ‘Events’ table links to various other tables via a string identifier. While convenient for developers, this approach is detrimental for long-term scientific data preservation. For a cultural heritage database to serve as a primary source for future scholarship—adhering to the ‘Archaeological Database Principle’—it must be self-documenting and rigorous. The proposed schema enforces strict Foreign Key constraints for every relationship. A transition event cannot exist unless it explicitly references valid input and output manifestation records. This prioritization of epistemological reliability ensures that the data remains valid and queryable for generations. 2 The Landscape of Digital Organology: A Critical Review To situate the Unified Initiative, we must rigorously evaluate the existing landscape of organ documentation. The field is currently characterized by high-quality but architecturally divergent projects, each optimized for specific local goals but collectively failing to provide a global, interoperable semantic web of data. 1 Pipe Organ Database Initiative Working Paper [v1] 2.1 The National Pipe Organ Register (NPOR) The National Pipe Organ Register (NPOR), managed by the Royal College of Organists (RCO) and the British Institute of Organ Studies (BIOS), represents the exemplar of the ‘census’ model [3]. With over 31,000 records, it is comprehensive in scope but limited by its structural origins. • Building Episodes: NPOR handles history through ‘Building Episodes,’ a chronological list of interventions [1]. While this provides a timeline, these episodes are often text-heavy descriptors rather than structured data events. • Component Tracking: The NPOR model does not strictly enforce unique identifiers for subcomponents (ranks, chests) across time. If a rank is moved from one organ to another, the connection is typically recorded in a ‘Remarks’ field. This ‘string-based’ linking prevents automated provenance research. • Fragmentation: The NPOR’s data exists as ‘snapshots’ of specifications [2]. This snapshot approach means that the continuity of the instrument is inferred by the user, not enforced by the schema. 2.2 The Organ Historical Society (OHS) Database The OHS Database, serving the North American context, mirrors the NPOR in scale but differs in philosophy [4]. Its evolution highlights the struggle to modernize legacy data structures. •Static vs. Dynamic: The OHS integration with the ‘Historic Organ Citations’ program reveals a bias toward the static artifact [5]. The database excels at describing organs that have not changed. • Modification Handling: The OHS citation guidelines ask applicants to describe modifications ‘in as much detail as possible’ [5], but this is primarily for the review panel’s judgment. The database structure often collapses the history of the instrument, obscuring the specific disposition at previous points in time. 2.3 Geographic and Typological Fragmentation Beyond the Anglosphere, the landscape of digital organology is characterized by a proliferation of national inventories and enthusiast portals, each employing divergent schemas. • National Inventories: Projects such as the Inventaire National des Orgues in France [6], Varhany a varhanáři in the Czech Republic [7], and the Orgelverzeichnis Schweiz [8] provide high-authority data but remain strictly bounded by national borders. They function as isolated administrative tools rather than nodes in a global network. • Crowdsourced Aggregators: Platforms like OrganIndex [9] and Die-Orgelseite [10] leverage wikistyle contributions to achieve impressive breadth. However, they often lack the rigorous authority control required for academic citation, frequently conflating historical states with current conditions. • Technical Thesauri: Resources such as the Encyclopedia of Organ Stops [11] exist as isolated lexicons. In the current landscape, a ‘Viola da Gamba’ stop listed in a Czech database has no semantic link to its definition in an external thesaurus, preventing automated comparative analysis of tonal dispositions. This fragmentation necessitates the ‘Ingestion Strategy’ proposed in Section 5, where such disparate sources are not replaced, but rather harvested and normalized into the Unified Schema. 2 Pipe Organ Database Initiative Working Paper [v1] 2.4 MIMO and the LIDO Schema Moving from national registers to museum collections, the Musical Instrument Museums Online (MIMO) project aggregates data from European museums using the LIDO (Lightweight Information Describing Objects) schema [12]. • The ‘Item’ Constraint: LIDO is designed for the exchange of metadata about museum objects, treating an object primarily as a discrete ‘Item’ [13]. • Composite Objects: While LIDO can describe ‘composite objects,’ it is not optimized for the deep, recursive complexity of a pipe organ (Organ →Division →Chest →Rank →Pipe). • Lack of Temporal Depth: LIDO is a descriptive format, not a management schema. It describes what an object is, but lacks the internal logic to enforce how an object changes state [14]. 2.5 Polifonia and Knowledge Graphs The Polifonia project represents the most advanced attempt to use Semantic Web technologies to link musical heritage data [15]. Its ‘Organs Pilot’ aims to extract knowledge graphs from encyclopedic text [16]. • Interoperability vs. Integrity: Polifonia uses an ontology network to link data across disparate sources. It excels at discovery—finding hidden connections between builders and composers. • Weaknesses: As an extraction and linking project, Polifonia inherits the quality issues of its sources. The Unified Initiative proposed here is distinct: it is a foundational layer designed to create rigorous primary data, which can then be exposed to the Polifonia network. 2.6 The musiXplora Project Developed at the Research Center DIGITAL ORGANOLOGY at Leipzig University, the musiXplora represents a paradigm shift from static registers to a dynamic, interactive research environment [17]. Unlike traditional census-based databases that function primarily as finding aids, musiXplora is designed as a multimodal system for information retrieval and knowledge preservation, specifically engineered to support the collaborative workflows of musicology [18]. • The Seven-Facet Ontology: The system organizes musicological knowledge into seven distinct, highly interconnected repositories: Musici (persons), Baccae (objects/instruments), Loci (places), Res (terms), Casae (institutions), Eventa (events), and Catalogus (media) [17]. This structure allows for deep semantic traversal; for example, an instrument is linked to its maker’s biography, the institutions that housed it, and specific events where it was used [19]. • Visual Analytics and Distant Reading: A defining feature of the project is its integration of ‘Distant Reading’ methodologies. By employing interactive visualizations—such as glyph-based maps and dynamic timelines—the platform enables researchers to identify large-scale trends invisible in text-based catalogues [20]. Recent applications include visualizing the geographical diffusion of the ‘Prague School’ of double bass players across ten generations or tracking the adaptation of the tuba in Bavaria [18]. • Enhanced Publications: The project pioneers the concept of ‘Enhanced Publications’ in organology. This model links academic publications directly to the underlying datasets, ensuring that the data supporting a hypothesis remains accessible and verifiable [21]. This ‘prospective’ digitization strategy contrasts with the ‘retrospective’ digitization often seen in legacy registers, promoting a workflow where digital tools support hypothesis generation rather than merely storage [21]. 3 Pipe Organ Database Initiative Working Paper [v1] 3 Theoretical Framework: A Realist Ontology for Cultural Heritage The Unified Initiative is not merely a database schema; it is the operationalization of a specific philosophical stance regarding the nature of existence for cultural artifacts, likely aligned with the Basic Formal Ontology (BFO). 3.1 The Continuant vs. The Manifestation The central principle of the schema is the decoupling of the Continuant from the Manifestation. The Continuant represents the enduring identity of the object (e.g., “The Organ of St. Bavokerk”), while the Manifestation represents a specific temporal slice of that identity (e.g., “The Organ of St. Bavokerk as modified by Muller in 1738”). CORE SCHEMA: IDENTITY & STATE core.continuant + id [PK] + code: "Organ of St. Bavo" + hierarchy_path + type_id core.manifestation + id [PK] + continuant_id [FK] + parent_id [FK] (Hierarchy) + location_id + description: "State in 1738" organs.pipe / sonus.oscillator + id [PK] + manifestation_id [FK] + musical_note_id + physics_parameters THE RELATIONAL BRIDGE core.activity + id [PK] + code: "Restoration Job" + type_id: Agent Action relations.activity_transition + id [PK] + activity_id [FK] + transition_id [FK] + context_provenance_id [FK] + precedence: Int ingestor.context_provenance + id [PK] + source_id: "NPOR_123" + json_path: "$.history[0]" + context_hash Verifies DYNAMICS: PHENOMENA dynamics.transition + id [PK] + in_manifestation_id [FK] + out_manifestation_id [FK] + severity_level + type_id: "Rebuild" Identity Composition Initiates Links To Input State Output State Figure 1: The Logical Architecture of MODAVIS Data. The diagram illustrates the ‘Relational Bridge’ architecture, which decouples the Identity (Continuant) from the State (Manifestation), and the Agent (Activity) from the Phenomenon (Dynamics). This triangulation is anchored by strict provenance, resolving the ‘Ship of Theseus’ paradox by treating historical events as verified claims rather than flat attributes. To strictly formalize the lifecycle of the object, the schema categorizes manifestations into three distinct ontological domains: Material, Abstract, and Surrogate. Transitive Manifestations: Model the object during production or modification phases. Every intervention by a builder creates a transitive state, capturing the evolution of the object before it fulfills its intended purpose. This class represents states where the object undergoes significant changes in properties or condition without losing its identity. Constitutive Manifestations: The state of the object upon completion or publication, where the intended purpose is first realized. This is the standard “active” state of a musical instrument. Fragmentary Manifestations: Occurring after the disintegration of the whole, a fragment remains a continuant but serves as a component in potential future manifestations. This explicitly models the mechanism of salvage and reconstruction common in organ history. 4 Pipe Organ Database Initiative Working Paper [v1] Conceptual Manifestations: Represent the object in its planning or design phase (e.g., technical drawings, contracts). These possess causal dependency on the intent of actors but lack material substance. Agential Manifestations: A category modeling the behavior of actors. This represents an entity (often a software agent or historical persona) acting within a specific role derived from a human actor. This enables the system to distinguish between the biological person and their specific professional configuration at a moment in time (e.g., “Silbermann the Apprentice” vs. “Silbermann the Master”). Digital Manifestations: A static digital representation (e.g., a scan, recording, or photograph) that documents a state but does not fulfill the object’s performative purpose. Virtual Manifestations: An interactive representation capable of fulfilling the instrument’s immersive purpose (e.g., a playable physics simulation). Unlike digital manifestations, these rely on variable parameters to simulate behavior in real-time. Hybrid Manifestations: Represent augmented objects where physical and virtual components merge, such as the projection of digital data onto a physical reconstruction, creating an interdependent phenomenological experience. 3.2 Juridical Personhood and Organizational Identity The Continuant-Manifestation distinction is not limited to physical instruments; it addresses a fundamental ontological challenge regarding organizations. Like pipe organs, organizations (builders, museums, committees) possess no material substrate for identity persistence. They are social constructs subject to the ”Ship of Theseus” paradox: an entity may change its name, its personnel, its mission, and its legal structure, yet persist as the same identity. The proposed schema models these entities by distinguishing between the Juridical Person (Level 1: ‘core.continuant‘) and the Organizational Configuration (Level 2: ‘core.manifestation‘). The Juridical Person represents the unbroken legal existence of the entity, while the Configuration represents its temporal state (e.g., ”The Royal Museum” vs. ”The National Institute”). Attribution events in the ‘dynamics‘ schema link to the Juridical Person, but the temporal timestamp of the event allows the system to resolve the specific Organizational Configuration operative at that moment. This dual-aspect model enables the precise tracking of provenance across mergers, dissolutions, and rebrandings. 3.3 The Epistemic Object and Social Attribution Beyond the physical materiality of the pipe organ, the database must account for the Social Object—an entity defined not by atoms, but by collective attribution and interaction [22]. In the context of organ history, the identity of an instrument is often constructed through the perspective attribution of its observers. The Unified Initiative implements the concept of the Epistemic Object [23]. In this model, a relationship stored in the database (e.g., ”Bach played this organ”) is not treated as an absolute boolean truth, but as a constructed object consisting of a Source, a Statement, and a Rationale. The schema operationalizes this via the dynamics.attribution and relations.activity_attribution tables. Here, an attribution is treated as a dynamic event where a community or individual assigns meaning or identity to a continuant. This allows the database to model conflicting truths: one source may attribute an instrument to Silbermann, while another attributes it to his pupils. By modeling these as separate epistemic objects linked to the same continuant, the database preserves the history of knowledge about the object, rather than flattening it into a single consensus reality. The schema operationalizes this via the ubiquitous context_provenance_id foreign key present on every relation table (e.g., relations.activity_attribution ). In this architecture, a fact is not a direct boolean property of an entity but a triangulated relationship between a source , a continuant , and a value , hashed cryptographically. This allows the database to hold contradictory states—such as two distinct 5 Pipe Organ Database Initiative Working Paper [v1] relations.manifestation_continuant entries asserting different builders—simultaneously, distinguished only by their provenance vector. 3.4 The Fragmentary Manifestation and Cyclic Lineage A crucial addition to this framework is the concept of the Fragmentary Manifestation. When an organ is dismantled, its components do not cease to exist; they become fragments. A Fragmentary Manifestation occurs after the disintegration of the original identity. To illustrate the power of this model over static text fields, consider an organ that is decommissioned, its pipes stored, and later incorporated into a new instrument. The Unified Model tracks this lineage unbroken: 1. Manifestation A (The Original): The organ exists in its initial constitutive state. 2. Event (Extraction): A dynamics.transition event records the removal of pipework, linked to the specific component. 3. State (Fragment): The pipes persist as a core.manifestation of the type ‘fragment’, possessing no parent organ but retaining their material identity. 4. Event (Incorporation): A subsequent event links the fragment to Manifestation B (The New Organ), seamlessly integrating the historical material into a new context. Technically, this is enforced through the coupled interaction of the dynamics.extraction and dynamics.incorporation entities. Unlike a simple ‘move’ event, the schema requires the termination of the source manifestation via an extraction relation, resulting in a core.manifestation of type_id fragment. This fragment preserves the continuant_id but lacks a parent. The subsequent incorporation event does not create a new object but strictly maps this existing continuant to the target instrument’s hierarchy, preserving the immutable row_hash of the original material. These fragments serve as the raw material for Derivative Manifestations, explicitly modeling the mechanism of salvage and reconstruction common in organ history. 4 The Unified Schema Architecture: A Technical Analysis The schema definition is a highly normalized, relational structure designed to enforce ontological commitments. • Core Schema (core’): Defines the primary entities. core.continuant includes hierarchy_path for optimizing tree traversals. Crucially, core.activity is introduced here to record the Historical Action (Who and Why), distinct from the physical change itself. Dynamics Schema (dynamics’): This schema is the engine of observable change. It records the Phenomenon (What happened) separate from the agent. It replaces generic ‘Events’ tables with specific, typed interaction tables such as dynamics.transition(qualitative state change),dynamics.displacement(spatial movement), anddynamics.assembly‘ (component addition). • Organs Schema (‘organs’): Domain-specific tables reflect the complexity of the instrument. organs.coupler explicitly models the connection between divisions, allowing for the computational reconstruction of the instrument’s routing. • Media and Sonus Schema (‘media’, ‘sonus’): Supports the ‘Virtual Acoustic Object’ (VAO) capabilities [24]. sonus.oscillator stores physical modeling parameters, indicating the database is designed for simulation as well as documentation. 6 Pipe Organ Database Initiative Working Paper [v1] 4.1 The Rejection of Polymorphism Modern web frameworks frequently employ polymorphic associations to link a generic ”Event” table to multiple entity types via string identifiers. The Unified Initiative explicitly rejects this pattern, arguing that it introduces a fundamental Category Error. A generic event table cannot enforce the distinct topological requirements of different phenomena. For instance, the dynamics.displacement entity requires strict spatial vectors ( origin_location_id , destination_location_id ), whereas a dynamics.transition requires state-change parameters (severity_level, affected_components). By implementing explicit relation tables—such as relations.activity_displacement versus relations.activity_transition —the schema enforces structural validity at the database level. An event cannot simply ”happen”; it must satisfy the dimensional constraints of its ontological category. Treating distinct phenomena—such as a qualitative state change (‘transition‘), a spatial movement (‘displacement‘), and a legal transfer (‘attribution‘)—as instances of a generic ”event” collapses their ontological distinctions. A displacement requires a trajectory; a transition requires a severity level; an attribution requires a juridical recipient. By implementing explicit relation tables (e.g., relations.transition_temporality versus relations.displacement_temporality ), the schema enforces semantic transparency. The database structure itself documents the ontological differences between phenomena, ensuring that the data remains interpretable even if the application layer is lost—a requirement of the Archaeological Database Principle. core.activity id [PK] code: ”Restoration 1850” description: ”Major overhaul...” type_id: Restoration relations.activity_transition id [PK] activity_id [FK] →core transition_id [FK] →dynamics context_provenance_id [FK] precedence: 1 dynamics.transition id [PK] in_manifestation_id [FK] out_manifestation_id [FK] severity_level: High description: ”Re-pitching of pipes” ingestor.context_provenance id [PK] source_id: ”NPOR_Rec_123” json_path: ”$.history[2].event” hash: 0x7f8a... Initiates Links to Phenomenon Verifies Claim The Epistemic Object (The Verified Claim) Strict Topology: Unlike a generic event, this table enforces specific columns for state transition (in/out). Figure 2: The Triangulation of Historical Events. The schema separates the Agent (core.activity) from the Phenomenon (dynamics.transition). They are linked by a dedicated Relation Table, which anchors the connection to a specific Provenance record. This structure prevents the ”Category Error” of polymorphic event tables and ensures every claim is traceable to a source document. 7 Pipe Organ Database Initiative Working Paper [v1] 4.2 Progressive Disclosure: Bridging Rigor and Usability The strict normalization required for database-level integrity (as argued in Section 1.2) inevitably results in a schema of high complexity. Constructing a human-readable object description from the atomic dynamics and relations tables often necessitates JOIN operations across ten or more entities. To reconcile this rigorous ontology with practical usability, the initiative employs a strategy of Progressive Disclosure implemented via a dedicated SQL Views schema. These views function not merely as conveniences, but as a stable Interface Layer (API Contract) between the data and the user. For instance, the view views.organ_full_component_list encapsulates the recursive logic required to traverse the core.continuant hierarchy, presenting a flattened, denormalized representation of the instrument for standard queries. This architecture explicitly decouples the Storage Model from the Presentation Model. It ensures that while the underlying data remains valid, atomic, and resistant to decay (satisfying the Archaeological Database Principle), the external interface remains accessible. This approach effectively hides the cognitive load of the ontological graph from the end-user while preserving the capability for deep, semantic traversal when required. 4.3 Multimodal Spatiality and Geographic Hierarchies While the organ is an architectural instrument, its data reality is often geographically fluid due to displacements and border shifts. To address this, the schema incorporates a dedicated geospatial module (geo schema) powered by PostGIS extensions. Unlike standard string-based address fields, this module enforces a strict separation between physical coordinates and administrative identities. The system implements a hierarchical localization strategy. Raw text input regarding location is processed through a multi-stage validation pipeline, querying open data services (e.g., OpenStreetMap, Nominatim) to resolve ambiguous toponyms. The resulting data is stored in geo.location, which holds the immutable spatial coordinates, and geo.administrative, which captures the political entity (city, region, country) applicable at the time of the event. This separation is crucial for historical accuracy. For example, an organ in Strasbourg may have geo.location coordinates that remain constant, while its linked relations.administrative_nationality changes between France and Germany throughout the 19th and 20th centuries. Furthermore, the schema supports Intermodal Segment Networking, where spatial definitions are not limited to map coordinates but extend to media localization—defining a ”location” as a specific pixel region in an image or a time-span in an audio file via the provenance.locality table, enabling precise spatial-temporal cross-referencing. 4.4 Comparative Alignment with Semantic Standards While MODAVIS prioritizes database-level integrity, it maintains semantic alignment with the Polifonia Organs Ontology to ensure future interoperability. Specifically, the Polifonia concept of the ‘Project’ (defined as a coherent set of tasks over time) finds its functional equivalent in the recursive architecture of the core.activity entity. Rather than utilizing a distinct aggregation container, such as an activity group, MODAVIS employs a self-referential hierarchy within the core.activity table. This allows atomic events (e.g., pipe extraction) to be subordinated to meso-level tasks (e.g., division restoration), which are in turn children of macro-level projects (e.g., 1850 Rebuild). This recursive granularity ensures that while the internal schema is optimized for atomic precision, it can easily map to the high-level ‘Project’ intervals utilized by semantic knowledge graphs. Furthermore, the temporal_bounds composite type is designed to be isomorphic with Polifonia’s core:TimeInterval , ensuring that fuzzy historical dates can be exported to Linked Open Data (LOD) networks without precision loss. 8 Pipe Organ Database Initiative Working Paper [v1] 7 Conclusion The transition from a fragmented landscape of digital organology to a unified, ontology-driven ecosystem is a necessary undertaking. The ‘Ship of Theseus’ nature of the pipe organ cannot be adequately captured by the static ‘census’ models of the 20th century. The Unified Initiative proposed here offers a robust solution. By enforcing the distinction between the enduring Continuant and the transient Manifestation, it provides a rigorous mathematical framework for modeling identity amidst change. By implementing a Transformation Ontology, it brings digital audio and virtual acoustic objects into the same sphere as physical pipes. This is more than a database update; it is the creation of a ‘Digital Twin’ infrastructure for the world’s organ heritage [24]. 15 Pipe Organ Database Initiative Working Paper [v1] References [1] Mike Sayers. “The National Pipe Organ Register 1992-2012”. In: Journal of the British Institute of Organ Studies 36 (2012), pp. 143–152. [2] Mike Sayers. NPOR 1992 to 2012: A History of Development. Tech. rep. British Institute of Organ Studies, 2012. url:https://storage.googleapis.com/npor-public/NPOR1992to2012.pdf. [3] British Institute of Organ Studies. The National Pipe Organ Register. 2024. url: https://npor.org.uk/ (visited on 01/01/2024). [4] Organ Historical Society. The OHS Pipe Organ Database. 2024. url: https://pipeorgandatabase. org/ (visited on 01/01/2024). [5] Organ Historical Society. National Registry for Historic Organs. 2024. url: https : / / organhistoricalsociety.org/historic-organs/national-registry/ (visited on 01/01/2024). [6] Association Orgue en France. Inventaire National des Orgues.url: https : / / inventaire - des - orgues.fr/ (visited on 11/19/2025). [7] Štěpán Svoboda. Varhany a varhanáři v České republice.url: http://www.varhany.net/ (visited on 11/19/2025). [8] Peter Fasler. Orgelverzeichnis Schweiz und Liechtenstein.url: http://peter-fasler.magix.net/ public/Orgelverzeichnis/ (visited on 11/19/2025). [9] OrganIndex: Die freie Orgeldatenbank.url:https://organindex.de/ (visited on 11/19/2025). [10] Martin Doering. Die-Orgelseite.url:https://die-orgelseite.de/ (visited on 11/19/2025). [11] Edward L. Stauff. Encyclopedia of Organ Stops.url: http://www.organstops.org/ (visited on 11/19/2025). [12] MIMO Consortium. MIMO Deliverable 2.1: Specification of the Data Model. Tech. rep. MIMO Consortium, 2010. url:https://mimo-international.com/documents/MIMO_Deliverable_2.1.pdf. [13] Erin Coburn, Richard Light, Gordon McKenna, and Regine Stein. LIDO - Lightweight Information Describing Objects, Version 1.0. 2010. url:http://www.lido-schema.org. [14] MIMO Consortium. Specific Tools to be used for Conversion and Adaptation of Proprietary Museum Data. Deliverable 3.6. Europeana, 2011. [15] Jacopo de Berardinis, Valentina Anita Carriero, Andrea Poltronieri, and Valentina Presutti. “The Polifonia Ontology Network: Building a Semantic Backbone for Musical Heritage”. In: The Semantic Web – ISWC 2023. Springer Nature Switzerland, 2023, pp. 302–322. doi: 10.1007/978-3-031-47243-5_17 . [16] Polifonia Project. ORGANS Pilot: Reconnect information on the histories and characteristics of historic organs. 2024. url: https://polifonia-project.github.io/ecosystem/pages/pilots/organs. html. [17] Richard Khulusi, Jakob Kusnick, Josef Focht, and Stefan Jänicke. “musiXplora: Visual Analysis of a Musicological Encyclopedia”. In: Proceedings of the 15th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications (IVAPP). Vol. 3. SCITEPRESS, 2020, pp. 76–87. doi:10.5220/0008977100760087. [18] David Fuhry, Vera Piontkowitz, Josef Focht, and Richard Khulusi. “MusiXplora: Visualizing Geospatial Data in the Musicological Domain”. In: LEVIA 22: Leipzig Symposium on Visualization in Applications (2022). Research Center Digital Organology, Leipzig University. [19] Richard Khulusi, Josef Focht, and Stefan Jänicke. MusiXplora: Accessing Digitized Musicological Linked Knowledge Through Visualization. Preprint. 2021. url: https://www.researchgate.net/ publication/360485601. [20] Richard Khulusi. “Zupfinstrumente in der visuellen Analyse ihrer Kontexte”. In: Phoibos: Zeitschrift für Zupfmusik 19 (2021), pp. 51–60. 16 Pipe Organ Database Initiative Working Paper [v1] [21] Josef Focht. “Zupfinstrumente in der Digital Organology”. In: Phoibos: Zeitschrift für Zupfmusik 19 (2021), pp. 7–23. [22] Herbert Blumer. Symbolic Interactionism: Perspective and Method. Englewood Cliffs, NJ: Prentice-Hall, 1969, p. 208. isbn: 9780138799243. [23] Hans-Jörg Rheinberger. Toward a History of Epistemic Things: Synthesizing Proteins in the Test Tube. Writing Science. Stanford, CA: Stanford University Press, 1997. isbn: 9780804727860. [24] Dominik Ukolov. “Reviving the Sounds of Sacral Environments: Personalized Real-Time Auralization and Visualization of Location-Based Virtual Acoustic Objects on Mobile Devices”. In: Workshop on Research and Education in Urban History in the Age of Digital Libraries. Springer. 2023, pp. 165–186. [25] OpenStreetMap Foundation. OpenStreetMap.url: https://www.openstreetmap.org (visited on 11/19/2025). [26] Marc Wick. GeoNames.url:https://www.geonames.org/ (visited on 11/19/2025). 17