Understand the data

Classification

How kinds and concepts organize the catalog.

Mnemo Atlas organizes entries in two ways. Kinds determine the facts an entry can hold. Concepts describe its style, subject, role, material, or other characteristics.

For example, the Empire State Building is a Building with the style Art Deco. Building supplies fields such as height and floors; Art Deco groups it with entries sharing that style.

How an entry is classified

First, identify what the record describes. Then choose the existing kind or kinds that fit its facts. Add concepts for the finer distinctions, and connections for its relationships to other entries.

Roles need separate treatment. Someone remains a Person before, during, and after holding office. The position and its dates describe a role, rather than a new kind of person.

If an imported record matches no registered kind, it is skipped and reported for review. Imports cannot invent new kinds.

Identify the subject

Question 1
Is it a temporary role or state?
Holding office, working as an architect, being demolished
If yes:
A dated role, or a date
Recorded on the entry with the years it applied. Barack Obama holds the position President of the United States, 2009–2017. A demolished building keeps its kind and gets an end date.
↓No
Question 2
Does it have facts of its own?
A height, a birth year, a launch price, a formula, a list of steps
If no:
A concept
A style, movement, period, genre, or material that classifies entries: Art Deco, Impressionism, the Baroque, limestone. If connections need to point to it, it can also have an entry of kind Concept, like Cubism.
↓Yes
Question 3
Which registered kinds fit its facts?
Person, Building, Product, Conflict, Recipe, and others
If none:
Skipped for review
Imports can only use registered kinds. A Wikidata item that matches none is skipped and listed in the import report for review. A new kind needs human approval first.
↓One or more

Then
Choose registered kinds
More than one kind when each applies: Trattoria da Enzo is both an Organization and a Place.
And
Add concepts
The Empire State Building: style Art Deco; materials steel, limestone, and granite.
And
Add connections
Each belongs to one of six connection families. A part of something larger stays its own entry with a part-of connection: the Pacific Theater is part of World War II.
Finally
Validate and review
Identity, kind, fields, and connection rules are checked. Some workflows store records as Proposed until a person accepts them. See how entries are added.

Choose an entry kind for the record's fields, concepts for its classifications, and connections for its relationships. The examples are real catalog records.

Examples

Subject	Classification	Why
Empire State Building	Building; Art Deco style	Its kind supplies building measurements; its style groups it with related work.
Ford F-150 generation	Product; pickup truck concept	Its specifications describe a manufactured product; the concept identifies the product category.
A president	Person; dated position	Holding office has a beginning and end without changing the person's kind.
World War II	Conflict	The record can describe participants, outcomes, and constituent conflicts.
Art Deco	Classification concept	It can classify many buildings and objects.
Cubism as a network subject	Concept entry linked to its classification concept	Connections can refer to the movement itself.
A restaurant	Organization and Place, where both apply	It can be a business and a location.
A recipe	Recipe	The entry describes a procedure and its steps.

The figure below shows more of these examples as they are recorded in the catalog, with their concepts and connections.

Empire State Building
Entry · Building
Concepts
Style: Art Deco · Materials: steel, limestone, granite
Connections
Located in Manhattan · Preceded by the Flatiron Building
Why
Holds its own facts (height, floors). Its style and materials are concepts, shared with other buildings.
Ford F-150 (13th gen)
Entry · Product
Concepts
Product class: Pickup truck
Connections
Part of the Ford F-Series · Preceded by the 12th generation
Why
Made as a line and compared by maker and specs, so a Product. Each generation is its own entry, linked in order.
Barack Obama
Entry · Person
Concepts
Position: President of the United States, 2009–2017 · Occupation: politician, lawyer
Connections
Preceded by George W. Bush · Influenced by Reinhold Niebuhr
Why
Being a person is permanent. President is a dated role: held from 2009 to 2017, and not before or after.
President of the United States
Dated role · Position
Why
A role someone can enter and leave. Recorded with dates on each person who held it.
World War II
Entry · Conflict
Concepts
Conflict type: world war · Outcome: victory
Why
Has participants and outcomes, and contains constituent conflicts (see the next example), so a Conflict rather than an Event.
Pacific Theater (WWII)
Entry · Conflict
Concepts
Conflict type: theater of war
Connections
Part of World War II
Why
A piece of a larger conflict is its own entry plus a part-of connection, not a sub-kind.
Ratification of the Eighteenth Amendment
Entry · Event
Connections
Caused the Eighteenth Amendment · Located in the United States
Why
A single happening with no parts inside it, so an Event.
Art Deco
Concept · Style
Why
Has no facts of its own; it classifies many buildings and objects.
Cubism
Entry · Concept
Connections
Influenced by Paul Cézanne and Impressionism · Part of modernism
Why
A movement, so a concept, and also an entry, because connections need to point at it.
Spaghetti alla Carbonara
Entry · Recipe
Concepts
Ingredients: guanciale, Pecorino Romano, egg
Why
The entry describes a procedure and its steps, not the dish on the plate, so it sits with the ideas.
Trattoria da Enzo
Entry · OrganizationEntry · Place
Why
A restaurant is both a business and somewhere you go, so it carries both kinds.
Transformer
Entry · Model
Concepts
Capabilities: language modeling, translation
Connections
Preceded by the recurrent neural network
Why
Holds a model's facts: architecture, parameters, training data.

Examples of kinds, concepts, and connections working together, as recorded in the catalog in September 2026. Select an entry's name to search for it.

Why some kinds are separate

Buildings and products are compared using different facts. A building has a site and floor count; a product may have a manufacturer and technical specifications. They can still share concepts and connections.

Written Work covers books, papers, and articles. Creative Work covers other creative forms such as paintings and films. Their fields differ, so they have separate kinds.

Conflict and Event also have different roles in this model. A conflict can contain constituent conflicts or events. Event represents an individual happening rather than a container for episodes. Longer sequences can be represented by a Nonfictional Story entry.

These are modeling choices for this catalog, not claims that there is only one correct way to classify the world.

People and organizationsenduring things

Organization
Fields: Founded · Type
Examples: Apple Inc., Nintendo, Deutscher Werkbund
Person
Fields: Nationality · Current city · Born · Died
Examples: Barack Obama, Dieter Rams, Paul Cézanne
Sports Team
Fields: Founded
Examples: no example in the catalog yet

Works and productsenduring things

Building
Fields: Building type · Height · Floors
Examples: Empire State Building, Barcelona Pavilion, Burj Khalifa
Product
Fields: Manufacturer · Horsepower · Payload · Launch price
Examples: Ford Model T, iPod mini, Tesla Model S
Model
Fields: Represents · Key variables · Assumptions · Domain of validity
Examples: Transformer, BERT, Black–Scholes model
Creative Work
Fields: Medium · Height · Width
Examples: Little black dress, Ubu roi, Tetris
Written Work
Fields: Form · Venue / publisher · Extent
Examples: On the Origin of Species, Volstead Act

Placesenduring things

Place
Fields: Place type · Population · Area
Examples: Manhattan, Chicago, Montjuïc

Events and storieshappenings

Conflict
Fields: Declaration · Casualties · Theater · Outcome
Examples: World War II, Korean War, Pacific Theater (WWII)
Event
Fields: Dates, a place and who took part
Examples: Ratification of the Eighteenth Amendment, Ice–albedo feedback
Nonfictional Story
Fields: A span of time, and the people, places and events inside it
Examples: 1929 Barcelona International Exposition
Fictional Story
Fields: A span of time, and the people, places and events inside it
Examples: no example in the catalog yet

Ideasideas

Equation
Fields: Expression · Variables · Domain of applicability
Examples: Bayes' theorem, Fundamental theorem of calculus
Concept
Fields: Nothing of its own: defined by its connections
Examples: Cubism, De Stijl, pop art
Recipe
Fields: Steps
Examples: Spaghetti alla Carbonara

Registered entry kinds and example fields. Availability in each view depends on the data recorded. Each color matches the one used for that kind across the site; select an example to search for it.

Movements, styles, periods, and roles

Concepts provide distinctions within and across kinds:

Movement: A shared cultural or intellectual project, such as Impressionism.
Style: A recognizable approach or form, such as Art Deco.
Period: A historical span, such as the Renaissance.
Genre: A category of work, such as portraiture.
Mode: A recurring approach, such as satire.
Role: A position or occupation associated with a person, with dates where recorded.

The same word can describe different ideas in different contexts. A broad movement and an architectural style should remain distinct when their meanings differ.

What makes something its own kind

New kinds need a clear reason to exist. Review considers whether they have useful fields of their own, enough comparable examples, a stable identity, and a meaningful distinction from existing kinds.

People currently make that decision. Software checks that stored records use registered kinds; it does not decide whether a proposed new kind is conceptually sound.

Concepts can be added more freely because they do not require a new entry schema.

Broad categories

The underlying model also distinguishes enduring things, happenings, ideas, and qualities. These broad categories help check whether combined kinds are compatible. They are not identical to the browsing groups shown on the Catalog landing page.

Corrections and disagreements

Classification involves judgment, and imported records can be misclassified. If an entry looks wrong, send a correction with its name or link and a useful source.

See How entries are added for the validation and review process.

← Documentation