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Classification

Hierarchical taxonomies for data governance - organizing tags into meaningful categories

Overview

The Classification entity represents a hierarchical taxonomy system for organizing tags. Classifications enable structured governance through categories like PII, Compliance, Data Quality, and Tier. Each classification contains a hierarchy of tags.

Relationship Diagram

graph TD
    %% Main entity
    CLASS[Classification<br/>PII]

    %% Primary tags
    CLASS -->|contains| TAG1[Tag<br/>Sensitive]
    CLASS -->|contains| TAG2[Tag<br/>NonSensitive]

    %% Nested tag hierarchy - Sensitive branch
    TAG1 -->|has child| TAG1A[Tag<br/>Email]
    TAG1 -->|has child| TAG1B[Tag<br/>SSN]
    TAG1 -->|has child| TAG1C[Tag<br/>CreditCard]
    TAG1 -->|has child| TAG1D[Tag<br/>BankAccount]

    %% Nested tag hierarchy - NonSensitive branch
    TAG2 -->|has child| TAG2A[Tag<br/>Name]
    TAG2 -->|has child| TAG2B[Tag<br/>PhoneNumber]
    TAG2 -->|has child| TAG2C[Tag<br/>Address]

    %% Governance relationships
    USR[System] -.->|provides| CLASS

    %% Applied to entities
    TAG1A -.->|classifies| COL1[Column<br/>customer_email]
    TAG1A -.->|classifies| COL2[Column<br/>user_email]
    TAG1B -.->|classifies| COL3[Column<br/>ssn]
    TAG2A -.->|classifies| COL4[Column<br/>first_name]
    TAG2A -.->|classifies| COL5[Column<br/>last_name]

    %% Applied to tables
    TAG1 -.->|classifies| TBL1[Table<br/>customer_pii]
    TAG2 -.->|classifies| TBL2[Table<br/>customer_profiles]

    %% Applied to other assets
    TAG1C -.->|classifies| DASH[Dashboard<br/>Payment Analytics]
    TAG1 -.->|classifies| ML[MLModel<br/>fraud_detector]

    %% Other classifications
    CLASS2[Classification<br/>Tier] -->|contains| TIER1[Tag<br/>Gold]
    CLASS2 -->|contains| TIER2[Tag<br/>Silver]
    CLASS2 -->|contains| TIER3[Tag<br/>Bronze]

    TIER1 -.->|classifies| TBL3[Table<br/>critical_data]
    TIER2 -.->|classifies| TBL4[Table<br/>standard_data]

    %% Styling
    classDef classification fill:#8B5CF6,stroke:#7C3AED,color:#fff
    classDef tag fill:#A78BFA,stroke:#8B5CF6,color:#fff
    classDef nestedTag fill:#DDD6FE,stroke:#A78BFA,color:#000
    classDef governance fill:#059669,stroke:#047857,color:#fff
    classDef data fill:#2563EB,stroke:#1E40AF,color:#fff

    class CLASS,CLASS2 classification
    class TAG1,TAG2,TIER1,TIER2,TIER3 tag
    class TAG1A,TAG1B,TAG1C,TAG1D,TAG2A,TAG2B,TAG2C nestedTag
    class USR governance
    class COL1,COL2,COL3,COL4,COL5,TBL1,TBL2,TBL3,TBL4,DASH,ML data

Schema Specifications

View the complete Classification schema in your preferred format:

Complete JSON Schema Definition

{
  "$id": "https://open-metadata.org/schema/entity/classification/classification.json",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "Classification",
  "description": "A `Classification` defines a hierarchical taxonomy of tags for data governance and organization.",
  "type": "object",
  "javaType": "org.openmetadata.schema.entity.classification.Classification",

  "definitions": {
    "provider": {
      "description": "Provider of the classification",
      "type": "string",
      "enum": ["System", "User"]
    },
    "mutuallyExclusive": {
      "description": "Tags in this classification are mutually exclusive",
      "type": "boolean",
      "default": false
    }
  },

  "properties": {
    "id": {
      "description": "Unique identifier",
      "$ref": "../../type/basic.json#/definitions/uuid"
    },
    "name": {
      "description": "Classification name",
      "$ref": "../../type/basic.json#/definitions/entityName"
    },
    "fullyQualifiedName": {
      "description": "Fully qualified name of the classification",
      "$ref": "../../type/basic.json#/definitions/fullyQualifiedEntityName"
    },
    "displayName": {
      "description": "Display name",
      "type": "string"
    },
    "description": {
      "description": "Markdown description of the classification purpose",
      "$ref": "../../type/basic.json#/definitions/markdown"
    },
    "provider": {
      "$ref": "#/definitions/provider"
    },
    "mutuallyExclusive": {
      "$ref": "#/definitions/mutuallyExclusive"
    },
    "tags": {
      "description": "Tags in this classification",
      "type": "array",
      "items": {
        "$ref": "../classification/tag.json"
      }
    },
    "disabled": {
      "description": "Whether this classification is disabled",
      "type": "boolean",
      "default": false
    },
    "version": {
      "description": "Metadata version",
      "$ref": "../../type/entityHistory.json#/definitions/entityVersion"
    }
  },

  "required": ["id", "name", "description"]
}

View Full JSON Schema →

RDF/OWL Ontology Definition

@prefix om: <https://open-metadata.org/schema/> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix owl: <http://www.w3.org/2001/XMLSchema#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .

# Classification Class Definition
om:Classification a owl:Class ;
    rdfs:subClassOf om:GovernanceAsset, skos:ConceptScheme ;
    rdfs:label "Classification" ;
    rdfs:comment "A hierarchical taxonomy system for organizing tags" ;
    om:hierarchyLevel 1 .

# Properties
om:classificationName a owl:DatatypeProperty ;
    rdfs:domain om:Classification ;
    rdfs:range xsd:string ;
    rdfs:label "name" ;
    rdfs:comment "Name of the classification" .

om:fullyQualifiedName a owl:DatatypeProperty ;
    rdfs:domain om:Classification ;
    rdfs:range xsd:string ;
    rdfs:label "fullyQualifiedName" ;
    rdfs:comment "Complete name of the classification" .

om:classificationProvider a owl:DatatypeProperty ;
    rdfs:domain om:Classification ;
    rdfs:range om:ClassificationProvider ;
    rdfs:label "provider" ;
    rdfs:comment "Provider: System or User" .

om:mutuallyExclusive a owl:DatatypeProperty ;
    rdfs:domain om:Classification ;
    rdfs:range xsd:boolean ;
    rdfs:label "mutuallyExclusive" ;
    rdfs:comment "Whether tags in this classification are mutually exclusive" .

om:isDisabled a owl:DatatypeProperty ;
    rdfs:domain om:Classification ;
    rdfs:range xsd:boolean ;
    rdfs:label "disabled" ;
    rdfs:comment "Whether this classification is disabled" .

om:hasTag a owl:ObjectProperty ;
    rdfs:domain om:Classification ;
    rdfs:range om:Tag ;
    rdfs:label "hasTag" ;
    rdfs:comment "Tags in this classification" ;
    owl:equivalentProperty skos:hasTopConcept .

# Provider Enumeration
om:ClassificationProvider a owl:Class ;
    owl:oneOf (
        om:SystemProvider
        om:UserProvider
    ) .

# Example Instances
ex:piiClassification a om:Classification, skos:ConceptScheme ;
    om:classificationName "PII" ;
    om:fullyQualifiedName "PII" ;
    om:displayName "Personally Identifiable Information" ;
    om:description "Classification for personally identifiable information" ;
    om:classificationProvider om:SystemProvider ;
    om:mutuallyExclusive false ;
    om:isDisabled false ;
    skos:hasTopConcept ex:sensitiveTag ;
    skos:hasTopConcept ex:nonSensitiveTag .

ex:tierClassification a om:Classification, skos:ConceptScheme ;
    om:classificationName "Tier" ;
    om:fullyQualifiedName "Tier" ;
    om:displayName "Data Tier" ;
    om:description "Data tier classification for priority and criticality" ;
    om:classificationProvider om:SystemProvider ;
    om:mutuallyExclusive true ;
    skos:hasTopConcept ex:goldTag ;
    skos:hasTopConcept ex:silverTag ;
    skos:hasTopConcept ex:bronzeTag .

View Full RDF Ontology →

JSON-LD Context and Example

{
  "@context": {
    "@vocab": "https://open-metadata.org/schema/",
    "om": "https://open-metadata.org/schema/",
    "skos": "http://www.w3.org/2004/02/skos/core#",
    "rdfs": "http://www.w3.org/2000/01/rdf-schema#",
    "xsd": "http://www.w3.org/2001/XMLSchema#",

    "Classification": "om:Classification",
    "ConceptScheme": "skos:ConceptScheme",
    "name": {
      "@id": "om:classificationName",
      "@type": "xsd:string"
    },
    "fullyQualifiedName": {
      "@id": "om:fullyQualifiedName",
      "@type": "xsd:string"
    },
    "displayName": {
      "@id": "om:displayName",
      "@type": "xsd:string"
    },
    "description": {
      "@id": "om:description",
      "@type": "xsd:string"
    },
    "provider": {
      "@id": "om:classificationProvider",
      "@type": "@vocab"
    },
    "mutuallyExclusive": {
      "@id": "om:mutuallyExclusive",
      "@type": "xsd:boolean"
    },
    "disabled": {
      "@id": "om:isDisabled",
      "@type": "xsd:boolean"
    },
    "tags": {
      "@id": "skos:hasTopConcept",
      "@type": "@id",
      "@container": "@set"
    }
  }
}

Example JSON-LD Instance:

{
  "@context": "https://open-metadata.org/context/classification.jsonld",
  "@type": ["Classification", "ConceptScheme"],
  "@id": "https://open-metadata.org/classifications/PII",

  "name": "PII",
  "fullyQualifiedName": "PII",
  "displayName": "Personally Identifiable Information",
  "description": "# PII Classification\n\nClassification for personally identifiable information to ensure compliance with privacy regulations.\n\n## Categories\n- **Sensitive**: Data requiring strict protection (SSN, financial info)\n- **NonSensitive**: Less critical personal data (name, public contact info)",
  "provider": "System",
  "mutuallyExclusive": false,
  "disabled": false,

  "tags": [
    {
      "@type": "Tag",
      "@id": "https://open-metadata.org/tags/PII/Sensitive",
      "name": "Sensitive",
      "fullyQualifiedName": "PII.Sensitive",
      "description": "Highly sensitive personal information",
      "children": [
        {
          "@type": "Tag",
          "@id": "https://open-metadata.org/tags/PII/Sensitive/Email",
          "name": "Email",
          "fullyQualifiedName": "PII.Sensitive.Email"
        },
        {
          "@type": "Tag",
          "@id": "https://open-metadata.org/tags/PII/Sensitive/SSN",
          "name": "SSN",
          "fullyQualifiedName": "PII.Sensitive.SSN"
        }
      ]
    },
    {
      "@type": "Tag",
      "@id": "https://open-metadata.org/tags/PII/NonSensitive",
      "name": "NonSensitive",
      "fullyQualifiedName": "PII.NonSensitive",
      "description": "Less sensitive personal information",
      "children": [
        {
          "@type": "Tag",
          "@id": "https://open-metadata.org/tags/PII/NonSensitive/Name",
          "name": "Name",
          "fullyQualifiedName": "PII.NonSensitive.Name"
        }
      ]
    }
  ]
}

View Full JSON-LD Context →

Use Cases

  • Organize data governance tags into hierarchical categories
  • Implement PII (Personally Identifiable Information) taxonomy
  • Define compliance classifications (GDPR, HIPAA, PCI-DSS)
  • Create data tier systems (Gold, Silver, Bronze)
  • Establish data quality categories
  • Build domain-specific taxonomies
  • Enforce mutually exclusive tag selection (e.g., only one tier per asset)
  • Support automated tag suggestions and propagation
  • Enable faceted search and filtering

JSON Schema Specification

Core Properties

id (uuid)

Type: string (UUID format) Required: Yes (system-generated) Description: Unique identifier for this classification

{
  "id": "3c4d5e6f-7a8b-4c9d-0e1f-2a3b4c5d6e7f"
}

name (entityName)

Type: string Required: Yes Pattern: ^[^.]*$ (no dots allowed) Min Length: 1 Max Length: 256 Description: Name of the classification

{
  "name": "PII"
}

fullyQualifiedName (fullyQualifiedEntityName)

Type: string Required: Yes (system-generated) Pattern: ^((?!::).)*$ Description: Fully qualified name of the classification

{
  "fullyQualifiedName": "PII"
}

displayName

Type: string Required: No Description: Human-readable display name

{
  "displayName": "Personally Identifiable Information"
}

description (markdown)

Type: string (Markdown format) Required: Yes Description: Rich text description of the classification's purpose

{
  "description": "# PII Classification\n\nClassification for personally identifiable information to ensure compliance with privacy regulations like GDPR, CCPA, and HIPAA.\n\n## Usage Guidelines\n- Apply to any data containing personal information\n- Use Sensitive subcategory for high-risk data\n- Triggers automated privacy scanning"
}

Configuration Properties

provider (Provider enum)

Type: string enum Required: No (default: User) Allowed Values:

  • System - System-provided classification (cannot be deleted)
  • User - User-defined classification (can be modified/deleted)
{
  "provider": "System"
}

mutuallyExclusive (boolean)

Type: boolean Required: No (default: false) Description: Whether only one tag from this classification can be applied to an asset

{
  "mutuallyExclusive": true
}

Example Use Case: Tier classification where an asset can only be Gold, Silver, or Bronze (not multiple)

disabled (boolean)

Type: boolean Required: No (default: false) Description: Whether this classification is disabled and hidden from users

{
  "disabled": false
}

Structure Properties

tags[] (Tag[])

Type: array of Tag objects Required: No Description: Hierarchical tags in this classification

Tag Object Properties (see Tag for full specification):

Property Type Required Description
name string Yes Tag name
displayName string No Display name
description markdown No Tag description
fullyQualifiedName string Yes Full tag path (e.g., PII.Sensitive.Email)
classification reference Yes Parent classification
parent reference No Parent tag (for nested tags)
children Tag[] No Child tags
disabled boolean No Whether tag is disabled

Example with Nested Hierarchy:

{
  "tags": [
    {
      "name": "Sensitive",
      "fullyQualifiedName": "PII.Sensitive",
      "displayName": "Sensitive PII",
      "description": "Highly sensitive personal information requiring strict access controls",
      "children": [
        {
          "name": "Email",
          "fullyQualifiedName": "PII.Sensitive.Email",
          "description": "Email addresses"
        },
        {
          "name": "SSN",
          "fullyQualifiedName": "PII.Sensitive.SSN",
          "description": "Social Security Numbers"
        },
        {
          "name": "CreditCard",
          "fullyQualifiedName": "PII.Sensitive.CreditCard",
          "description": "Credit card numbers and payment information"
        }
      ]
    },
    {
      "name": "NonSensitive",
      "fullyQualifiedName": "PII.NonSensitive",
      "displayName": "Non-Sensitive PII",
      "description": "Less critical personal information",
      "children": [
        {
          "name": "Name",
          "fullyQualifiedName": "PII.NonSensitive.Name",
          "description": "Person names"
        },
        {
          "name": "PhoneNumber",
          "fullyQualifiedName": "PII.NonSensitive.PhoneNumber",
          "description": "Phone numbers"
        }
      ]
    }
  ]
}

Versioning Properties

version (entityVersion)

Type: number Required: Yes (system-managed) Description: Metadata version number, incremented on changes

{
  "version": 1.5
}

updatedAt (timestamp)

Type: integer (Unix epoch milliseconds) Required: Yes (system-managed) Description: Last update timestamp

{
  "updatedAt": 1704240000000
}

updatedBy (string)

Type: string Required: Yes (system-managed) Description: User who made the update

{
  "updatedBy": "admin"
}

Complete Example

PII Classification (Non-Mutually Exclusive)

{
  "id": "3c4d5e6f-7a8b-4c9d-0e1f-2a3b4c5d6e7f",
  "name": "PII",
  "fullyQualifiedName": "PII",
  "displayName": "Personally Identifiable Information",
  "description": "Classification for personally identifiable information",
  "provider": "System",
  "mutuallyExclusive": false,
  "disabled": false,
  "tags": [
    {
      "name": "Sensitive",
      "fullyQualifiedName": "PII.Sensitive",
      "description": "Highly sensitive personal information",
      "children": [
        {
          "name": "Email",
          "fullyQualifiedName": "PII.Sensitive.Email"
        },
        {
          "name": "SSN",
          "fullyQualifiedName": "PII.Sensitive.SSN"
        }
      ]
    },
    {
      "name": "NonSensitive",
      "fullyQualifiedName": "PII.NonSensitive",
      "description": "Less sensitive personal information",
      "children": [
        {
          "name": "Name",
          "fullyQualifiedName": "PII.NonSensitive.Name"
        }
      ]
    }
  ],
  "version": 1.5,
  "updatedAt": 1704240000000,
  "updatedBy": "admin"
}

Tier Classification (Mutually Exclusive)

{
  "id": "4d5e6f7a-8b9c-4d0e-1f2a-3b4c5d6e7f8a",
  "name": "Tier",
  "fullyQualifiedName": "Tier",
  "displayName": "Data Tier",
  "description": "Data tier classification for priority and criticality",
  "provider": "System",
  "mutuallyExclusive": true,
  "disabled": false,
  "tags": [
    {
      "name": "Gold",
      "fullyQualifiedName": "Tier.Gold",
      "description": "Mission-critical data with highest priority"
    },
    {
      "name": "Silver",
      "fullyQualifiedName": "Tier.Silver",
      "description": "Important data with medium priority"
    },
    {
      "name": "Bronze",
      "fullyQualifiedName": "Tier.Bronze",
      "description": "Standard data with normal priority"
    }
  ],
  "version": 1.0,
  "updatedAt": 1704240000000,
  "updatedBy": "admin"
}

RDF Representation

Ontology Class

@prefix om: <https://open-metadata.org/schema/> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix owl: <http://www.w3.org/2001/XMLSchema#> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .

om:Classification a owl:Class ;
    rdfs:subClassOf om:GovernanceAsset, skos:ConceptScheme ;
    rdfs:label "Classification" ;
    rdfs:comment "A hierarchical taxonomy system for organizing tags" ;
    om:hasProperties [
        om:name "string" ;
        om:description "string" ;
        om:provider "ClassificationProvider" ;
        om:mutuallyExclusive "boolean" ;
        om:tags "Tag[]" ;
    ] .

Instance Example

@prefix om: <https://open-metadata.org/schema/> .
@prefix ex: <https://open-metadata.org/classifications/> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .

ex:PII a om:Classification, skos:ConceptScheme ;
    om:classificationName "PII" ;
    om:fullyQualifiedName "PII" ;
    om:displayName "Personally Identifiable Information" ;
    om:description "Classification for personally identifiable information" ;
    om:classificationProvider om:SystemProvider ;
    om:mutuallyExclusive false ;
    om:isDisabled false ;
    skos:hasTopConcept ex:PII_Sensitive ;
    skos:hasTopConcept ex:PII_NonSensitive .

ex:PII_Sensitive a om:Tag, skos:Concept ;
    skos:inScheme ex:PII ;
    skos:prefLabel "Sensitive" ;
    skos:narrower ex:PII_Sensitive_Email ;
    skos:narrower ex:PII_Sensitive_SSN .

JSON-LD Context

{
  "@context": {
    "@vocab": "https://open-metadata.org/schema/",
    "om": "https://open-metadata.org/schema/",
    "skos": "http://www.w3.org/2004/02/skos/core#",
    "Classification": "om:Classification",
    "ConceptScheme": "skos:ConceptScheme",
    "name": "om:classificationName",
    "description": "om:description",
    "provider": "om:classificationProvider",
    "mutuallyExclusive": "om:mutuallyExclusive",
    "tags": "skos:hasTopConcept"
  }
}

JSON-LD Example

{
  "@context": "https://open-metadata.org/context/classification.jsonld",
  "@type": ["Classification", "ConceptScheme"],
  "@id": "https://open-metadata.org/classifications/PII",
  "name": "PII",
  "fullyQualifiedName": "PII",
  "displayName": "Personally Identifiable Information",
  "provider": "System",
  "mutuallyExclusive": false,
  "tags": [
    {
      "@type": "Tag",
      "@id": "https://open-metadata.org/tags/PII/Sensitive"
    }
  ]
}

Relationships

Child Entities

  • Tag: Primary category tags in this classification
  • Tag (nested): Sub-category tags

Associated Entities

  • DataAsset: Tables, columns, dashboards, etc. tagged with tags from this classification

Custom Properties

This entity supports custom properties through the extension field. Common custom properties include:

  • Data Classification: Sensitivity level
  • Cost Center: Billing allocation
  • Retention Period: Data retention requirements
  • Application Owner: Owning application/team

See Custom Properties for details on defining and using custom properties.

API Operations

Create Classification

POST /api/v1/classifications
Content-Type: application/json

{
  "name": "Compliance",
  "displayName": "Compliance & Regulatory",
  "description": "Classification for compliance and regulatory requirements",
  "provider": "User",
  "mutuallyExclusive": false,
  "tags": [
    {
      "name": "GDPR",
      "description": "General Data Protection Regulation"
    },
    {
      "name": "HIPAA",
      "description": "Health Insurance Portability and Accountability Act"
    }
  ]
}

Get Classification

GET /api/v1/classifications/name/PII?fields=tags

Update Classification

PATCH /api/v1/classifications/{id}
Content-Type: application/json-patch+json

[
  {
    "op": "add",
    "path": "/tags/-",
    "value": {
      "name": "Financial",
      "description": "Financial personal information"
    }
  }
]

List Classifications

GET /api/v1/classifications?fields=tags&limit=25

Disable Classification

PATCH /api/v1/classifications/{id}
Content-Type: application/json-patch+json

[
  {
    "op": "replace",
    "path": "/disabled",
    "value": true
  }
]

Common Classification Examples

System Classifications

  1. PII - Personally Identifiable Information
  2. Tier - Data criticality (Gold/Silver/Bronze)
  3. Compliance - Regulatory frameworks
  4. DataQuality - Data quality indicators
  5. Sensitivity - Data sensitivity levels

User-Defined Classifications

  1. BusinessDomain - Business area categorization
  2. DataLifecycle - Data lifecycle stages
  3. AccessControl - Access restriction levels
  4. DataSource - Source system categorization
  • Tag - Individual tags within classifications
  • GlossaryTerm - Business terminology
  • Glossary - Business vocabulary containers
  • Table - Applying tags to tables
  • SKOS Standard - W3C Simple Knowledge Organization System