One organ, many identities: learn the ontology
Start with the Cuntz organ and one documented pipe observation. Follow the distinction between an object, its representations and the claims we make about it—without needing to know graph terminology first.
The running example is the Cuntz positive organ, mXp 4010243. Each example starts with a concrete question, explains the relevant concept in ordinary language, and works through the reasoning. The full steps are expandable elsewhere in the notebooks; here they are open so the argument can be read continuously.
1. Separate the object from descriptions of it
Cuntz · Worked example#
Is the 3D model the Cuntz organ?
An ontology is an explicit agreement about the kinds of things we describe and the relationships between them. Its first useful distinction here is between an instrument and a representation of it.
The physical Cuntz positive organ is identified as mXp 4010243. The release also contains a geometric model and audio files. They concern the instrument, but each has its own identity.
Work through the example 3 STEPS
Name the physical subject
Use the instrument identity for claims about the organ itself. Its record can link to the museum and to documentary evidence.
Name each representation
Give a model, a recording and a playable software product separate identities. A relationship such as “represents this instrument” connects them without declaring them the same thing.
Follow a change
Compressing the model changes its digital realization. It does not rebuild the museum instrument. Repairing a physical component is a different event and needs its own evidence.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- MODAVIS Ontology Network 0.1.0 ↗
Identity, state, configuration, evidence, assertions, context and provenance. Teaching examples explain its distinctions without inventing new normative properties.
The displayed model is a derived visualization with an unverified physical scale. Being about the Cuntz organ does not make every visible detail a measured historical fact.
The useful distinction. An identity answers “which thing?”; a representation relationship answers “what is this about?”.
Cuntz · Worked example#
Which Cuntz are we describing?
A state describes an instrument at a particular phase; a configuration describes how its components are arranged and function together. Context limits where a statement applies.
The thesis distinguishes the physical description of four registers and 180 pipes from an analyzed digital configuration with five register labels and 225 recordings. The published VAO also inventories 225 pipe entities.
Work through the example 3 STEPS
Keep the descriptions attributed
Record the historical description, digital analysis configuration and published inventory with their respective sources. Their numbers concern different documented accounts.
Ask the state and counting question
Determine which phase, configuration and counting convention each account describes before comparing totals. A virtual register label is not by itself an additional original physical register.
Retain the unresolved mapping
The thesis identifies a missing mapping, particularly for Regal 8′. Keep that unresolved relation visible. A structured manifest records its inventory but does not independently settle the historical discrepancy.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)
Submitted dissertation, 11 September 2026; §§8.2.2.1 and 8.4.1, printed pp. 264–265 and 275–276. The historical description and digital inventory require a resolved mapping; the manuscript is not redistributed here.
- MODAVIS Ontology Network 0.1.0 ↗
Identity, state, configuration, evidence, assertions, context and provenance. Teaching examples explain its distinctions without inventing new normative properties.
This example does not assert that the organ underwent a particular rebuild or that an extra original register existed.
The useful distinction. A well-formed record can preserve disagreement accurately while the historical interpretation remains open.
2. Follow a real observation to its evidence
Cuntz · Worked example#
What exactly does “1281” tell us?
An observation connects a property and a result to the thing observed. A unit gives the number a physical interpretation; a source selector identifies its evidential location.
The published Cuntz manifest contains an observation for rank:ged:pipe:key-036 with property code GesL, value 1281, unit MilliM, and source-cell flag Holzgedackt 8!D9.
Work through the example 3 STEPS
Identify the subject and property
The number belongs to the specified pipe entity and the workbook’s GesL property. It is not a dimension of the complete organ or an arbitrary distance on the screen.
Retain value and unit together
The stored value is 1281 millimetres. Converting it gives 1.281 metres; keep that conversion separate from the original source value and unit.
Locate the source
The observation links to the exact workbook realization, the measurement activity and the cell selector. A later reader can check the entry and consult the workbook’s definition of GesL.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- VAO Standard 0.5.0 ↗
The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2.
The example reproduces a release observation; it does not independently remeasure the pipe or supply a calibration uncertainty that the record does not provide.
The useful distinction. A reusable measurement needs a subject, property, value, unit and evidence location.
Cuntz · Worked example#
Is the workbook timestamp the measurement date?
Provenance describes how a record came into being. Applicability describes when a claim concerns its subject. A file timestamp is a third, potentially different fact.
The same Cuntz observation carries 2020-09-16T10:33:05Z and flags identifying the result time as a workbook modification timestamp, with a source series marked 2019.
Work through the example 3 STEPS
Read the qualification
The measurement activity explicitly says its timestamp is the workbook modification time, not an asserted measurement-session time.
Preserve the distinctions
Keep the source-series label, the workbook timestamp and any independently documented session date as separate information. Do not turn the most precise-looking timestamp into the date the pipe was measured.
Ask the right query
A query for files modified in 2020 can use this timestamp. A query for instruments measured during 2020 needs evidence of session dates and cannot silently use the same field.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- MODAVIS Ontology Network 0.1.0 ↗
Identity, state, configuration, evidence, assertions, context and provenance. Teaching examples explain its distinctions without inventing new normative properties.
No exact acquisition date is inferred from the timestamp in this example.
The useful distinction. Precision of formatting is not precision of historical knowledge.
3. Make the relationships explicit
Cuntz · Worked example#
What does a knowledge graph add to a catalogue entry?
A graph stores named things and explicit relationships. RDF expresses a statement as a subject, a relationship and an object; many such statements can share the same subject.
Consider the Cuntz pipe represented as rank:ged:pipe:key-036. A measurement, a source workbook and an activity can all refer to it without being squeezed into one text field.
Work through the example 3 STEPS
Start with a plain sentence
“This observation concerns that pipe.” Here the observation is the subject, the feature-of-interest relationship connects it to the pipe, and the pipe is the object.
Connect the evidence
The observation points to the measurement activity and raw-result workbook realization. The activity names Philipp Hosbach as its agent. These links answer different questions: what was observed, where it came from and who is credited.
Ask a connected question
A reader can follow the pipe to an observation, then to the workbook cell, unit and processing history. That chain is more useful than merely finding the same word in several descriptions.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- MODAVIS Ontology Network 0.1.0 ↗
Identity, state, configuration, evidence, assertions, context and provenance. Teaching examples explain its distinctions without inventing new normative properties.
These sentences explain graph structure. They are not a copy-and-paste RDF serialization or a claim that English relationship labels are normative ontology terms.
The useful distinction. A graph makes relationships addressable and traversable; it does not make the linked assertions automatically true.
Cuntz · Worked example#
Why keep a long identifier when a name would be easier?
An identifier distinguishes a thing independently of the label displayed to readers. An IRI is an identifier written in a form that can also be used in linked data.
The public instrument link is https://musixplora.de/mxp/4010243. The VAO manifest uses the package entity identifier urn:musixplora:4010243:cuntz-positiv:instrument. These serve related but different identifying roles.
Work through the example 3 STEPS
Keep the readable label
Show “Cuntz positive organ” in the notebook. A translated or corrected label can change without changing the subject.
Preserve the link between records
Retain the external instrument identifier and the package entity identifier with their declared relationship. Do not infer that every mention of “Cuntz” identifies this object.
Inspect properties, not identifier spelling
The release retains a rights-record identifier ending in “restricted-review”, while its actual access property says “open” and specifies CC BY-SA 4.0. The opaque identifier suffix is not the access decision.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- MODAVIS Ontology Network 0.1.0 ↗
Identity, state, configuration, evidence, assertions, context and provenance. Teaching examples explain its distinctions without inventing new normative properties.
A URL, URN and DOI are not interchangeable promises. The instrument link identifies the subject; the version DOI identifies a particular released dataset.
The useful distinction. Read the record’s explicit properties; do not derive meaning or permissions from a convenient label or identifier suffix.
Cuntz · Worked example#
How did the model on this page come into being?
Provenance is a trace of inputs, transformations, outputs and responsible agents. PROV-O provides a vocabulary for describing those roles.
The published Cuntz release identifies an FBX source model and a derived GLB runtime model. This notebook displays a further web derivative of that released GLB.
Work through the example 3 STEPS
Fix the input
Before preparing the web model, compare its source bytes and SHA-256 with the exact published runtime realization. A similar filename is insufficient.
Describe the transformation
For this website, the texture is resized to at most 2048 pixels and encoded as JPEG. Duplicate and unused resources are removed, and meshopt compression applies quantization. These changes are documented with the derivative.
Give the output its own identity
The web file has its own byte size and digest. It remains linked to the source release and source realization, while being described as a display derivative rather than the unmodified archived GLB.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- VAO Standard 0.5.0 ↗
The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2.
Compression and a rendered appearance do not establish geometric measurement accuracy or recover the object’s original appearance.
The useful distinction. A derivative can be useful and traceable without being byte-identical to its source.
4. Keep interpretation and validation accountable
Cuntz · Worked example#
How can two accounts disagree without corrupting the database?
An assertion is an attributable claim. A review decision records how that claim is interpreted; a projection is a selected view of the reviewed knowledge.
The Cuntz thesis description and the digital inventory present different register counts. Treating the latest imported count as an unconditional replacement would erase the question the discrepancy raises.
Work through the example 3 STEPS
Store both claims with their scope
Retain the four-register physical description and the five-label digital configuration, including their sources and intended subjects.
Review the relationship
Ask whether the accounts concern comparable states and counting units. The missing Regal 8′ mapping remains an explicit review issue rather than an invented explanation.
Publish an understandable view
A catalogue summary can show a selected statement and its qualification, while an evidence view exposes the other assertion and the reason the relationship remains unresolved.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- MODAVIS Ontology Network 0.1.0 ↗
Identity, state, configuration, evidence, assertions, context and provenance. Teaching examples explain its distinctions without inventing new normative properties.
- Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)
Submitted dissertation, 11 September 2026; §§8.2.2.1 and 8.4.1, printed pp. 264–265 and 275–276. The historical description and digital inventory require a resolved mapping; the manuscript is not redistributed here.
This is a teaching application of the assertion model, not a claim that a new authoritative review of the historical register mapping has been completed.
The useful distinction. A clean interface can present an editorial decision without deleting the evidence behind competing interpretations.
Cuntz · Worked example#
When is “we do not know yet” the useful result?
Abstention means withholding an unsupported assignment while keeping the evidence available. It differs from asserting that a claim is false.
The Cuntz thesis identifies a missing mapping for the fifth digital register label. A system may preserve that label without deciding which historical physical register it represents.
Work through the example 3 STEPS
Keep the observed record
The digital label and its associated recordings remain available, with their source and release identity.
Withhold the unsupported link
Do not assign the label to a historical register merely to make every field complete. Record that the correspondence is unresolved, along with the reason.
Define what could change the decision
A suitable mapping manifest or additional attributable evidence could support a later reviewed assignment. Preserve the earlier state so the change remains inspectable.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- MODAVIS Ontology Network 0.1.0 ↗
Identity, state, configuration, evidence, assertions, context and provenance. Teaching examples explain its distinctions without inventing new normative properties.
- Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)
Submitted dissertation, 11 September 2026; §§8.2.2.1 and 8.4.1, printed pp. 264–265 and 275–276. The historical description and digital inventory require a resolved mapping; the manuscript is not redistributed here.
Abstention here does not mean that the recording is unusable or that the fifth label is historically false.
The useful distinction. An unresolved relation is useful information when its evidence and the next required check are explicit.
Cuntz · Worked example#
What can OWL and SHACL check about this organ?
OWL describes meanings and logical relationships between classes. SHACL checks whether a particular data graph satisfies specified constraints. Neither performs the historical investigation.
Suppose an import mistakenly uses one identifier for both the physical Cuntz organ and its playable virtual-instrument package. This is an illustrative error, not a reported defect in the published release.
Work through the example 3 STEPS
Explain the semantic distinction
The ontology treats the physical instrument and playable virtual entities as distinct kinds. An object and a package representing it must not collapse into one identity.
Check the supplied graph
A SHACL validation run checks the relevant shapes and expected data. It can report the mistaken identity assignment or a missing required relationship so the author can correct the record.
Return to source criticism
Passing those checks does not determine whether the fifth register label corresponds to an original register. That question needs an evidence mapping, not another shape check.
BASIS FOR THIS EXAMPLE
- MODAVIS Ontology Network 0.1.0 ↗
Identity, state, configuration, evidence, assertions, context and provenance. Teaching examples explain its distinctions without inventing new normative properties.
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
The error is hypothetical. Validation outcomes depend on the declared ontology, shapes and validation setup; no new official MODAVIS constraint is introduced here.
The useful distinction. Validation checks the modeling contract; research establishes whether an interpretation is warranted.
Cuntz · Worked example#
Does the word “organ” settle the classification?
A controlled vocabulary supplies identified concepts and labels. SKOS describes concepts and their relationships; OMARO additionally retains perspectives, source assertions and review status.
“Cuntz positive organ” is a label for a particular instrument. “Positive organ” is also a type concept that may occur in a vocabulary. A label match connects a research question, not automatically an identity.
Work through the example 3 STEPS
Separate object from concept
The museum organ is a physical subject. The vocabulary concept describes a kind of instrument. Many objects can be described using one concept.
Keep the classification attributable
If a source classifies the Cuntz instrument, record the source and relevant instrument state. Do not infer an exact Hornbostel–Sachs code merely from a familiar English label.
Retain source words during normalization
A source stop label such as Holzgedackt 8′ remains evidence even when a normalized concept is added. The proposed mapping needs the documented pitch, division and context.
BASIS FOR THIS EXAMPLE
- MODAVIS Ontology Network 0.1.0 ↗
Identity, state, configuration, evidence, assertions, context and provenance. Teaching examples explain its distinctions without inventing new normative properties.
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- OMARO 0.1.0 ↗
No new OMARO assertion or Hornbostel–Sachs classification of the Cuntz instrument is claimed in this example.
The useful distinction. A vocabulary improves comparison by identifying meanings while preserving the source’s wording.
Sources & further reading
- Cuntz Positiv · VAO 0.5.0-rc.2
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- MODAVIS Ontology Network 0.1.0
Identity, state, configuration, evidence, assertions, context and provenance. Teaching examples explain its distinctions without inventing new normative properties.
- Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)
Submitted dissertation, 11 September 2026; §§8.2.2.1 and 8.4.1, printed pp. 264–265 and 275–276. The historical description and digital inventory require a resolved mapping; the manuscript is not redistributed here.
Page editions 2026-09-r5 ↓
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