Add auxiliary enums and slots for digital platforms and physical locations

- Created AuxiliaryDigitalPlatformTypeEnum.yaml to classify types of secondary digital platforms.
- Created AuxiliaryPlaceTypeEnum.yaml to classify types of secondary physical locations.
- Added OrganizationBranchTypeEnum.yaml for formal organizational branches at auxiliary locations.
- Introduced auxiliary_places.yaml slot to link CustodianPlace to subordinate physical locations.
- Introduced auxiliary_platforms.yaml slot to link DigitalPlatform to subordinate digital properties.
- Added located_at.yaml slot to connect OrganizationalStructure to physical locations.

schemas/20251121/linkml/modules/classes/AuxiliaryDigitalPlatform.yaml

@@ -0,0 +1,610 @@
+# Heritage Auxiliary Digital Platform Class
+# Represents subordinate/project-based digital platforms of a heritage custodian
+# DCAT: dcat:Catalog for secondary digital services
+
+id: https://nde.nl/ontology/hc/class/auxiliary-digital-platform
+name: auxiliary-digital-platform-class
+title: AuxiliaryDigitalPlatform Class
+
+imports:
+  - linkml:types
+  - ./Custodian
+  - ./DigitalPlatform
+  - ./CustodianObservation
+  - ./ReconstructionActivity
+  - ./TimeSpan
+  - ../enums/AuxiliaryDigitalPlatformTypeEnum
+
+prefixes:
+  linkml: https://w3id.org/linkml/
+  hc: https://nde.nl/ontology/hc/
+  schema: http://schema.org/
+  dcat: http://www.w3.org/ns/dcat#
+  dcterms: http://purl.org/dc/terms/
+  foaf: http://xmlns.com/foaf/0.1/
+  prov: http://www.w3.org/ns/prov#
+  skos: http://www.w3.org/2004/02/skos/core#
+
+classes:
+  AuxiliaryDigitalPlatform:
+    class_uri: dcat:Catalog
+    description: >-
+      Subordinate or project-based digital platform associated with a heritage custodian.
+      
+      **CRITICAL DISTINCTION - THREE-TIER DIGITAL PLATFORM MODEL**:
+      
+      1. **DigitalPlatform** (main digital entry point):
+         - Primary web presence of the custodian
+         - Main website, primary API, flagship digital platform
+         - Like CustodianPlace is the preferred place reference
+         - Examples: rijksmuseum.nl, europeana.eu, nationaalarchief.nl
+         
+      2. **AuxiliaryDigitalPlatform** (subordinate platforms) - THIS CLASS:
+         - Secondary digital properties: project sites, exhibition microsites
+         - Like CustodianAppellation is to CustodianName
+         - Examples: project websites, temporary exhibition portals, specialized tools
+         
+      3. **DigitalPlatformType** (custodian type classification):
+         - For digital-FIRST custodians (no physical building)
+         - Applied at Custodian.custodian_type level
+         - Examples: Europeana (aggregation platform), Internet Archive
+      
+      **DCAT ALIGNMENT**:
+      
+      `dcat:Catalog` - "A curated collection of metadata about datasets"
+      
+      Key properties:
+      - `dcat:dataset` - links to datasets/collections
+      - `dcat:service` - data services provided
+      - `dcterms:isPartOf` - links to parent catalog
+      
+      **RELATIONSHIP TO DIGITALPLATFORM**:
+      
+      AuxiliaryDigitalPlatform represents SUBORDINATE digital presence
+      DigitalPlatform represents PRIMARY digital entry point
+      
+      ```
+      Custodian (hub)
+        │
+        └── digital_platform → DigitalPlatform (main digital entry)
+            └── auxiliary_platforms → AuxiliaryDigitalPlatform (project sites)
+      ```
+      
+      **USE CASES**:
+      
+      1. **Project Websites**:
+         - Rijksmuseum → Rijksstudio API (separate from main website)
+         - National Archives → WW2 Portal (thematic project)
+      
+      2. **Exhibition Microsites**:
+         - Temporary exhibition with dedicated website
+         - Virtual tour for specific collection
+      
+      3. **Specialized Tools/Apps**:
+         - Mobile app (separate from responsive website)
+         - Collection browser tool
+         - Crowdsourcing platform
+      
+      4. **Legacy/Archived Platforms**:
+         - Previous website versions
+         - Deprecated APIs still in use
+      
+      5. **Grant-Funded Projects**:
+         - EU-funded digitization project portal
+         - Research project data portal
+      
+      6. **Educational Platforms**:
+         - Teacher resources portal
+         - Student learning modules
+         - Workshop booking system
+      
+      **Example - Rijksmuseum Auxiliary Platforms**:
+      ```yaml
+      Custodian:
+        hc_id: "https://nde.nl/ontology/hc/nl-nh-ams-m-rm-q190804"
+        preferred_label: "Rijksmuseum"
+        digital_platform:
+          - platform_name: "Rijksmuseum Website"
+            homepage_web_address: "https://www.rijksmuseum.nl/"
+            auxiliary_platforms:
+              - platform_name: "Rijksstudio"
+                auxiliary_platform_type: PROJECT_WEBSITE
+                platform_url: "https://www.rijksmuseum.nl/nl/rijksstudio"
+                platform_purpose: "Personal collection creation and high-res image downloads"
+              - platform_name: "Rijksmuseum Data API"
+                auxiliary_platform_type: API_ENDPOINT
+                platform_url: "https://data.rijksmuseum.nl/"
+                platform_purpose: "Developer access to collection metadata and images"
+              - platform_name: "Night Watch Experience"
+                auxiliary_platform_type: EXHIBITION_MICROSITE
+                platform_url: "https://www.rijksmuseum.nl/en/stories/operation-night-watch"
+                platform_purpose: "Interactive exploration of Night Watch research project"
+      ```
+      
+      **TEMPORAL VALIDITY**:
+      
+      Auxiliary platforms often have finite lifespans:
+      - Exhibition microsite: opens with exhibition, archived after closure
+      - Project portal: funded period, then deprecated or integrated
+      - Legacy platforms: valid_to when replaced by new system
+    
+    exact_mappings:
+      - dcat:Catalog
+    
+    close_mappings:
+      - schema:WebSite
+      - dcat:DataService
+      - foaf:Document
+    
+    related_mappings:
+      - dcterms:isPartOf
+      - schema:isRelatedTo
+      - dcat:servesDataset
+    
+    slots:
+      - auxiliary_platform_id
+      - platform_name
+      - auxiliary_platform_type
+      - platform_url
+      - platform_purpose
+      - platform_description
+      - api_documentation
+      - technology_stack
+      - is_auxiliary_of
+      - provides_access_to
+      - related_project
+      - funding_source
+      - iiif_support
+      - linked_data
+      - valid_from
+      - valid_to
+      - temporal_extent
+      - archival_status
+      - archived_at
+      - was_derived_from
+      - was_generated_by
+      - refers_to_custodian
+    
+    slot_usage:
+      auxiliary_platform_id:
+        slot_uri: dcterms:identifier
+        description: >-
+          Unique identifier for this auxiliary digital platform.
+          Format: URI following NDE Heritage Custodian ontology conventions.
+        range: uriorcurie
+        required: true
+        identifier: true
+        examples:
+          - value: "https://nde.nl/ontology/hc/aux-platform/rijksmuseum-rijksstudio"
+            description: "Rijksstudio platform ID"
+      
+      platform_name:
+        slot_uri: dcterms:title
+        description: >-
+          Name of this auxiliary digital platform.
+          
+          Dublin Core: title for resource name.
+          
+          This is the human-readable name of the secondary platform.
+        range: string
+        required: true
+        examples:
+          - value: "Rijksstudio"
+            description: "Personal collection tool"
+          - value: "Operation Night Watch"
+            description: "Research project microsite"
+          - value: "WW2 Portal"
+            description: "Thematic archive portal"
+      
+      auxiliary_platform_type:
+        slot_uri: dcterms:type
+        description: >-
+          Type of auxiliary platform using AuxiliaryDigitalPlatformTypeEnum.
+          
+          Types include:
+          - PROJECT_WEBSITE: Dedicated project site
+          - EXHIBITION_MICROSITE: Temporary exhibition portal
+          - API_ENDPOINT: Programmatic interface (separate from main API)
+          - MOBILE_APP: Native or hybrid mobile application
+          - COLLECTION_BROWSER: Specialized collection exploration tool
+          - CROWDSOURCING_PLATFORM: User contribution portal
+          - EDUCATIONAL_PORTAL: Learning resources
+          - DATA_PORTAL: Dataset download/access
+          - LEGACY_PLATFORM: Deprecated but maintained platform
+          - VIRTUAL_TOUR: 360° or immersive experience
+          
+          Dublin Core: type for classification.
+        range: AuxiliaryDigitalPlatformTypeEnum
+        required: true
+        examples:
+          - value: "PROJECT_WEBSITE"
+            description: "Project site type"
+          - value: "EXHIBITION_MICROSITE"
+            description: "Exhibition microsite type"
+      
+      platform_url:
+        slot_uri: foaf:homepage
+        description: >-
+          URL of this auxiliary digital platform.
+          
+          FOAF: homepage for web address.
+          
+          This is the entry point URL for the platform.
+        range: uri
+        required: true
+        pattern: "^https?://"
+        examples:
+          - value: "https://www.rijksmuseum.nl/nl/rijksstudio"
+            description: "Rijksstudio URL"
+          - value: "https://data.rijksmuseum.nl/"
+            description: "Data API URL"
+      
+      platform_purpose:
+        slot_uri: dcterms:description
+        description: >-
+          Brief description of what this platform provides/enables.
+          
+          Dublin Core: description for purpose statement.
+          
+          Focus on user benefit and functionality.
+        range: string
+        examples:
+          - value: "Personal collection creation and high-res image downloads"
+            description: "Rijksstudio purpose"
+          - value: "Interactive exploration of Night Watch research project"
+            description: "Exhibition microsite purpose"
+      
+      platform_description:
+        slot_uri: dcterms:abstract
+        description: >-
+          Detailed description of this auxiliary platform.
+          
+          Dublin Core: abstract for longer description.
+          
+          Include:
+          - Full functionality description
+          - Target audience
+          - Technical requirements
+          - Relationship to main platform
+        range: string
+        examples:
+          - value: "Rijksstudio allows users to create personal collections from the Rijksmuseum's digitized artworks, download high-resolution images, and share curated sets with others."
+            description: "Detailed platform description"
+      
+      api_documentation:
+        slot_uri: dcat:endpointDescription
+        description: >-
+          URL to API documentation (for API-type platforms).
+          
+          DCAT: endpointDescription for API documentation.
+        range: uri
+        examples:
+          - value: "https://data.rijksmuseum.nl/object-metadata/api/"
+            description: "API documentation URL"
+      
+      technology_stack:
+        slot_uri: schema:programmingLanguage
+        description: >-
+          Technologies used to build this platform.
+          
+          Schema.org: programmingLanguage for technical implementation.
+          
+          Include frameworks, languages, services.
+        range: string
+        multivalued: true
+        examples:
+          - value: "React"
+            description: "Frontend framework"
+          - value: "Python/Django"
+            description: "Backend stack"
+      
+      is_auxiliary_of:
+        slot_uri: dcterms:isPartOf
+        description: >-
+          Link back to the DigitalPlatform that this is an auxiliary of.
+          
+          Dublin Core: isPartOf links part to whole.
+          
+          Like CustodianAppellation.variant_of_name → CustodianName,
+          this links AuxiliaryDigitalPlatform → DigitalPlatform (main platform).
+        range: DigitalPlatform
+        required: true
+        examples:
+          - value: "https://nde.nl/ontology/hc/platform/rijksmuseum-website"
+            description: "Main Rijksmuseum website"
+      
+      provides_access_to:
+        slot_uri: dcat:servesDataset
+        description: >-
+          Collections or datasets accessible through this platform.
+          
+          DCAT: servesDataset for data service relationship.
+          
+          Link to CustodianCollection or dataset identifiers.
+        range: uriorcurie
+        multivalued: true
+        examples:
+          - value: "https://nde.nl/ontology/hc/collection/rm-paintings"
+            description: "Paintings collection"
+      
+      related_project:
+        slot_uri: dcterms:isPartOf
+        description: >-
+          Research project or initiative this platform supports.
+          
+          Dublin Core: isPartOf for project relationship.
+          
+          Useful for grant-funded or research project platforms.
+        range: string
+        examples:
+          - value: "Operation Night Watch"
+            description: "Research project name"
+          - value: "EU Horizon 2020 Grant #123456"
+            description: "Grant reference"
+      
+      funding_source:
+        slot_uri: schema:funder
+        description: >-
+          Organization or grant funding this platform.
+          
+          Schema.org: funder for funding relationship.
+        range: string
+        examples:
+          - value: "European Commission Horizon 2020"
+            description: "EU funding"
+          - value: "Mondriaan Fund"
+            description: "Dutch cultural fund"
+      
+      iiif_support:
+        slot_uri: dcterms:conformsTo
+        description: >-
+          Does this platform support IIIF?
+          
+          Dublin Core: conformsTo for standard compliance.
+        range: boolean
+        examples:
+          - value: true
+            description: "IIIF enabled"
+      
+      linked_data:
+        slot_uri: dcterms:conformsTo
+        description: >-
+          Does this platform provide linked open data?
+          
+          Dublin Core: conformsTo for LOD compliance.
+        range: boolean
+        examples:
+          - value: true
+            description: "Provides RDF/JSON-LD"
+      
+      valid_from:
+        slot_uri: schema:validFrom
+        description: >-
+          Date when this auxiliary platform was launched.
+          
+          Track when project sites, microsites opened.
+        range: date
+        examples:
+          - value: "2018-06-01"
+            description: "Platform launched June 2018"
+      
+      valid_to:
+        slot_uri: schema:validThrough
+        description: >-
+          Date when this auxiliary platform was decommissioned.
+          
+          NULL if still active.
+          
+          Important for temporary exhibition sites and project portals.
+        range: date
+        examples:
+          - value: "2021-12-31"
+            description: "Exhibition site closed end of 2021"
+      
+      temporal_extent:
+        slot_uri: crm:P4_has_time-span
+        description: >-
+          Temporal period during which this platform was operational.
+          
+          CIDOC-CRM: P4_has_time-span for fuzzy temporal boundaries.
+        range: TimeSpan
+        examples:
+          - value:
+              begin_of_the_begin: "2018-01-01"
+              end_of_the_end: "2021-12-31"
+            description: "Project period 2018-2021"
+      
+      archival_status:
+        slot_uri: schema:creativeWorkStatus
+        description: >-
+          Current status of platform if no longer active.
+          
+          Schema.org: creativeWorkStatus for lifecycle status.
+          
+          Values:
+          - ACTIVE: Currently operational
+          - DEPRECATED: Still accessible but not maintained
+          - ARCHIVED: Preserved in web archive
+          - OFFLINE: No longer accessible
+        range: string
+        examples:
+          - value: "ARCHIVED"
+            description: "Preserved in web archive"
+          - value: "DEPRECATED"
+            description: "Still accessible but not maintained"
+      
+      archived_at:
+        slot_uri: schema:archivedAt
+        description: >-
+          URL to archived version (e.g., Internet Archive Wayback Machine).
+          
+          Schema.org: archivedAt for archive location.
+        range: uri
+        examples:
+          - value: "https://web.archive.org/web/20211231/https://example.nl/exhibition/"
+            description: "Wayback Machine URL"
+      
+      was_derived_from:
+        slot_uri: prov:wasDerivedFrom
+        description: >-
+          CustodianObservation(s) documenting this platform.
+          
+          PROV-O: wasDerivedFrom for observation provenance.
+        range: CustodianObservation
+        multivalued: true
+        required: false
+      
+      was_generated_by:
+        slot_uri: prov:wasGeneratedBy
+        description: >-
+          ReconstructionActivity that generated this platform record.
+          
+          PROV-O: wasGeneratedBy for generation activity.
+        range: ReconstructionActivity
+        required: false
+      
+      refers_to_custodian:
+        slot_uri: dcterms:references
+        description: >-
+          The Custodian hub that operates this auxiliary platform.
+          
+          Dublin Core: references for entity reference.
+          
+          All auxiliary platforms MUST reference the main custodian hub.
+        range: Custodian
+        required: true
+        examples:
+          - value: "https://nde.nl/ontology/hc/nl-nh-ams-m-rm-q190804"
+            description: "Rijksmuseum custodian hub"
+    
+    comments:
+      - "AuxiliaryDigitalPlatform models SUBORDINATE digital properties"
+      - "DigitalPlatform models PRIMARY digital entry point"
+      - "Analogous to CustodianAppellation for alternative names"
+      - "DCAT dcat:Catalog for secondary data catalogs/services"
+      - "Temporal validity tracks platform lifecycle (launched/deprecated/archived)"
+      - "Links back to DigitalPlatform via is_auxiliary_of"
+      - "Important for project-based and exhibition microsites with finite lifespans"
+    
+    see_also:
+      - "https://www.w3.org/TR/vocab-dcat-2/#Class:Catalog"
+      - "https://www.w3.org/TR/vocab-dcat-2/#Property:catalog_service"
+      - "https://schema.org/archivedAt"
+    
+    examples:
+      - value:
+          auxiliary_platform_id: "https://nde.nl/ontology/hc/aux-platform/rijksmuseum-rijksstudio"
+          platform_name: "Rijksstudio"
+          auxiliary_platform_type: PROJECT_WEBSITE
+          platform_url: "https://www.rijksmuseum.nl/nl/rijksstudio"
+          platform_purpose: "Personal collection creation and high-res image downloads"
+          platform_description: "Rijksstudio allows users to create personal collections from the Rijksmuseum's digitized artworks, download high-resolution images, and share curated sets with others."
+          is_auxiliary_of: "https://nde.nl/ontology/hc/platform/rijksmuseum-website"
+          provides_access_to:
+            - "https://nde.nl/ontology/hc/collection/rm-paintings"
+            - "https://nde.nl/ontology/hc/collection/rm-prints"
+          iiif_support: true
+          linked_data: false
+          valid_from: "2012-10-01"
+          archival_status: "ACTIVE"
+          refers_to_custodian: "https://nde.nl/ontology/hc/nl-nh-ams-m-rm-q190804"
+        description: "Rijksstudio personal collection platform"
+      
+      - value:
+          auxiliary_platform_id: "https://nde.nl/ontology/hc/aux-platform/rijksmuseum-data-api"
+          platform_name: "Rijksmuseum Data API"
+          auxiliary_platform_type: API_ENDPOINT
+          platform_url: "https://data.rijksmuseum.nl/"
+          platform_purpose: "Developer access to collection metadata and images"
+          api_documentation: "https://data.rijksmuseum.nl/object-metadata/api/"
+          technology_stack:
+            - "REST"
+            - "JSON"
+          is_auxiliary_of: "https://nde.nl/ontology/hc/platform/rijksmuseum-website"
+          iiif_support: true
+          linked_data: true
+          valid_from: "2013-03-01"
+          archival_status: "ACTIVE"
+          refers_to_custodian: "https://nde.nl/ontology/hc/nl-nh-ams-m-rm-q190804"
+        description: "Rijksmuseum developer API"
+      
+      - value:
+          auxiliary_platform_id: "https://nde.nl/ontology/hc/aux-platform/rm-night-watch-experience"
+          platform_name: "Operation Night Watch"
+          auxiliary_platform_type: EXHIBITION_MICROSITE
+          platform_url: "https://www.rijksmuseum.nl/en/stories/operation-night-watch"
+          platform_purpose: "Interactive exploration of Night Watch research project"
+          related_project: "Operation Night Watch"
+          funding_source: "ING Bank"
+          is_auxiliary_of: "https://nde.nl/ontology/hc/platform/rijksmuseum-website"
+          iiif_support: true
+          valid_from: "2019-07-01"
+          archival_status: "ACTIVE"
+          refers_to_custodian: "https://nde.nl/ontology/hc/nl-nh-ams-m-rm-q190804"
+        description: "Night Watch research project microsite"
+      
+      - value:
+          auxiliary_platform_id: "https://nde.nl/ontology/hc/aux-platform/na-ww2-portal"
+          platform_name: "WW2 Archives Portal"
+          auxiliary_platform_type: PROJECT_WEBSITE
+          platform_url: "https://www.nationaalarchief.nl/onderzoeken/zoekhulpen/ww2"
+          platform_purpose: "Thematic portal for World War 2 archival research"
+          platform_description: "Specialized portal providing access to WW2-related archives including resistance records, persecution documents, and liberation materials."
+          is_auxiliary_of: "https://nde.nl/ontology/hc/platform/nationaal-archief-website"
+          provides_access_to:
+            - "https://nde.nl/ontology/hc/collection/na-resistance-archives"
+            - "https://nde.nl/ontology/hc/collection/na-liberation-photos"
+          valid_from: "2015-05-05"
+          archival_status: "ACTIVE"
+          refers_to_custodian: "https://nde.nl/ontology/hc/nl-na"
+        description: "National Archives WW2 thematic portal"
+
+# Slot definitions (basic - detailed in class slot_usage)
+slots:
+  auxiliary_platform_id:
+    description: Unique identifier for auxiliary digital platform
+    range: uriorcurie
+  
+  auxiliary_platform_type:
+    description: Type of auxiliary platform
+    range: AuxiliaryDigitalPlatformTypeEnum
+  
+  platform_url:
+    description: URL of auxiliary platform
+    range: uri
+  
+  platform_purpose:
+    description: Brief purpose statement
+    range: string
+  
+  api_documentation:
+    description: URL to API documentation
+    range: uri
+  
+  technology_stack:
+    description: Technologies used
+    range: string
+  
+  is_auxiliary_of:
+    description: Link to main DigitalPlatform
+    range: DigitalPlatform
+  
+  provides_access_to:
+    description: Collections/datasets accessible
+    range: uriorcurie
+  
+  related_project:
+    description: Related research project
+    range: string
+  
+  funding_source:
+    description: Funding organization/grant
+    range: string
+  
+  archival_status:
+    description: Current status (ACTIVE/DEPRECATED/ARCHIVED/OFFLINE)
+    range: string
+  
+  archived_at:
+    description: URL to archived version
+    range: uri

schemas/20251121/linkml/modules/classes/CustodianPlace.yaml

@@ -11,10 +11,12 @@ imports:
   - ./CustodianObservation
   - ./ReconstructionActivity
   - ./FeaturePlace
+  - ./AuxiliaryPlace
   - ./Country
   - ./Subregion
   - ./Settlement
   - ../enums/PlaceSpecificityEnum
+  - ../slots/auxiliary_places
 
 slots:
   place_name:
@@ -123,6 +125,7 @@ classes:
       - subregion
       - settlement
       - has_feature_type
+      - auxiliary_places
       - was_derived_from
       - was_generated_by
       - refers_to_custodian
@@ -310,6 +313,58 @@ classes:
           - value: "https://nde.nl/ontology/hc/feature/herenhuis-mansion"
             description: "Links 'het herenhuis' place to MANSION feature type"
       
+      auxiliary_places:
+        slot_uri: org:hasSite
+        description: >-
+          Subordinate or secondary physical locations associated with this main CustodianPlace.
+          
+          **W3C ORG Alignment**:
+          
+          `org:hasSite` - "Indicates a site at which the Organization has some presence"
+          
+          **Hierarchical Pattern - Mirrors CustodianName/CustodianAppellation**:
+          
+          - CustodianPlace (main headquarters) → primary org:Site
+          - AuxiliaryPlace (subordinate sites) → secondary org:Site instances
+          
+          Like CustodianAppellation provides alternative names for CustodianName,
+          AuxiliaryPlace provides subordinate locations for CustodianPlace.
+          
+          **Use Cases**:
+          
+          1. **Off-site Storage**: Museum depot, archive annex
+          2. **Branch Locations**: Regional library branches, satellite galleries
+          3. **Specialized Facilities**: Conservation lab, digitization center
+          4. **Temporary Locations**: Exhibition pavilions, renovation storage
+          
+          **Relationship to OrganizationBranch**:
+          
+          AuxiliaryPlace → hosts_branch → OrganizationBranch
+          
+          Physical location (AuxiliaryPlace) hosts formal organizational unit (OrganizationBranch).
+          
+          **Example - Rijksmuseum**:
+          ```yaml
+          CustodianPlace:
+            place_name: "Rijksmuseum"
+            auxiliary_places:
+              - place_name: "Depot Amersfoort"
+                auxiliary_place_type: STORAGE_FACILITY
+              - place_name: "Rijksmuseum Schiphol"
+                auxiliary_place_type: BRANCH_OFFICE
+          ```
+        range: AuxiliaryPlace
+        multivalued: true
+        inlined_as_list: true
+        required: false
+        examples:
+          - value:
+              - place_name: "Depot Amersfoort"
+                auxiliary_place_type: STORAGE_FACILITY
+              - place_name: "Rijksmuseum Schiphol"
+                auxiliary_place_type: BRANCH_OFFICE
+            description: "Rijksmuseum subordinate locations"
+      
       was_derived_from:
         slot_uri: prov:wasDerivedFrom
         description: >-
@@ -379,6 +434,8 @@ classes:
       - "Distinct from Location class which has lat/lon coordinates"
       - "Can be vague ('the mansion') or specific ('het museum op het Museumplein 1')"
       - "Historical place names capture how custodians were referenced in archival documents"
+      - "NEW: auxiliary_places links to subordinate AuxiliaryPlace sites (depots, branches, labs)"
+      - "Hierarchical pattern mirrors CustodianName → CustodianAppellation relationship"
     
     see_also:
       - "http://www.cidoc-crm.org/html/cidoc_crm_v7.1.3.html#E53"

schemas/20251121/linkml/modules/classes/DigitalPlatform.yaml

@@ -11,7 +11,9 @@ imports:
   - ./CustodianObservation
   - ./ReconstructionActivity
   - ./DigitalPlatformType
+  - ./AuxiliaryDigitalPlatform
   - ./TimeSpan
+  - ../slots/auxiliary_platforms
 
 prefixes:
   linkml: https://w3id.org/linkml/
@@ -131,6 +133,7 @@ classes:
       - linked_data
       - metadata_standards
       - access_restrictions
+      - auxiliary_platforms
       - temporal_extent
       - was_derived_from
       - was_generated_by
@@ -421,6 +424,67 @@ classes:
           - value: "API key required"
             description: "Developer registration needed"
       
+      auxiliary_platforms:
+        slot_uri: dcterms:hasPart
+        description: >-
+          Subordinate or project-based digital platforms associated with this main DigitalPlatform.
+          
+          **DCAT Alignment**:
+          
+          `dcterms:hasPart` - Links main catalog/platform to sub-catalogs.
+          
+          **Hierarchical Pattern - Mirrors CustodianName/CustodianAppellation**:
+          
+          - DigitalPlatform (main entry point) → primary foaf:homepage
+          - AuxiliaryDigitalPlatform (project sites) → secondary platforms
+          
+          Like CustodianAppellation provides alternative names for CustodianName,
+          AuxiliaryDigitalPlatform provides subordinate platforms for DigitalPlatform.
+          
+          **Use Cases**:
+          
+          1. **Project Websites**: Research project portals, grant-funded sites
+          2. **Exhibition Microsites**: Temporary exhibition portals, virtual tours
+          3. **APIs and Tools**: Developer APIs, collection browsers, mobile apps
+          4. **Legacy/Archived**: Previous website versions, deprecated systems
+          5. **Educational Portals**: Teacher resources, learning modules
+          
+          **Example - Rijksmuseum**:
+          ```yaml
+          DigitalPlatform:
+            platform_name: "Rijksmuseum Website"
+            homepage_web_address: "https://www.rijksmuseum.nl/"
+            auxiliary_platforms:
+              - platform_name: "Rijksstudio"
+                auxiliary_platform_type: PROJECT_WEBSITE
+              - platform_name: "Rijksmuseum Data API"
+                auxiliary_platform_type: API_ENDPOINT
+              - platform_name: "Night Watch Experience"
+                auxiliary_platform_type: EXHIBITION_MICROSITE
+          ```
+          
+          **Temporal Considerations**:
+          
+          Auxiliary platforms often have finite lifespans:
+          - Exhibition microsite opens/closes with exhibition
+          - Project portals run during funding period
+          - Legacy platforms archived but accessible
+          
+          Each AuxiliaryDigitalPlatform tracks archival_status and archived_at.
+        range: AuxiliaryDigitalPlatform
+        multivalued: true
+        inlined_as_list: true
+        required: false
+        examples:
+          - value:
+              - platform_name: "Rijksstudio"
+                auxiliary_platform_type: PROJECT_WEBSITE
+                platform_url: "https://www.rijksmuseum.nl/nl/rijksstudio"
+              - platform_name: "Rijksmuseum Data API"
+                auxiliary_platform_type: API_ENDPOINT
+                platform_url: "https://data.rijksmuseum.nl/"
+            description: "Rijksmuseum subordinate digital platforms"
+      
       temporal_extent:
         slot_uri: crm:P4_has_time-span
         description: >-
@@ -488,6 +552,8 @@ classes:
       - "Multivalued on Custodian: one custodian can have multiple platforms (website + API + mobile app)"
       - "Temporal validity tracks platform lifecycle (launch, shutdown, migration)"
       - "IIIF and linked data flags enable discovery of interoperable platforms"
+      - "NEW: auxiliary_platforms links to subordinate AuxiliaryDigitalPlatform sites (project portals, microsites, APIs)"
+      - "Hierarchical pattern mirrors CustodianName → CustodianAppellation relationship"
     
     see_also:
       - "https://schema.org/WebSite"

schemas/20251121/linkml/modules/classes/OrganizationalStructure.yaml

@@ -5,6 +5,11 @@
 id: https://nde.nl/ontology/hc/class/OrganizationalStructure
 name: OrganizationalStructure
 
+imports:
+  - linkml:types
+  - ./AuxiliaryPlace
+  - ../slots/located_at
+
 classes:
   OrganizationalStructure:
     class_uri: org:OrganizationalUnit
@@ -67,6 +72,7 @@ classes:
       - staff_count
       - staff_members
       - managed_collections
+      - located_at
       - contact_point
       - valid_from
       - valid_to
@@ -364,6 +370,66 @@ classes:
                 extent: "1,200 objects"
             description: "Collection managed by Paintings Department"
       
+      located_at:
+        slot_uri: org:basedAt
+        range: AuxiliaryPlace
+        multivalued: true
+        inlined_as_list: true
+        description: >-
+          Physical location (AuxiliaryPlace) where this organizational unit operates.
+          
+          **W3C ORG Alignment**:
+          
+          `org:basedAt` - "Indicates the site at which the Organization has its main 
+          administrative/operational presence."
+          
+          **Optional Slot**:
+          
+          Many organizational units don't have fixed locations:
+          - Strategic Planning Committee (meets virtually)
+          - Research Fellowship Program (no physical space)
+          
+          Only use when organizational unit has identifiable physical location.
+          
+          **Use Cases**:
+          
+          1. **Departments at Branch Locations**:
+             - Conservation Team → located at Amersfoort Depot
+             - Digitization Team → located at off-site facility
+          
+          2. **Teams Spanning Multiple Locations**:
+             - IT Department → located at main building AND data center
+             - Public Services → located at main reading room AND annex
+          
+          **Relationship to OrganizationBranch**:
+          
+          OrganizationalStructure.located_at provides OPTIONAL location link.
+          OrganizationBranch.has_operational_unit provides hierarchical structure.
+          
+          ```
+          AuxiliaryPlace
+            └── hosts_branch → OrganizationBranch
+                └── has_operational_unit → OrganizationalStructure
+          
+          OrganizationalStructure
+            └── located_at → AuxiliaryPlace (optional, direct link)
+          ```
+          
+          **Example**:
+          ```yaml
+          OrganizationalStructure:
+            unit_name: "Conservation Division"
+            unit_type: DIVISION
+            located_at:
+              - place_name: "Conservation Lab - Main Building"
+              - place_name: "Climate-Controlled Storage - Depot"
+          ```
+        examples:
+          - value:
+              - place_name: "Depot Amersfoort"
+                auxiliary_place_type: STORAGE_FACILITY
+            description: "Organizational unit located at off-site storage"
+      
       contact_point:
         range: string
         description: >-
@@ -410,6 +476,8 @@ classes:
       - "Units can be nested via parent_unit (hierarchical structure)"
       - "Temporal validity tracks organizational changes"
       - "NOT for legally registered sub-organizations (use CustodianLegalStatus)"
+      - "NEW: located_at links organizational units to AuxiliaryPlace locations (optional)"
+      - "Enables tracking which departments/teams operate at which physical sites"
     
     examples:
       - value:

schemas/20251121/linkml/modules/enums/AuxiliaryDigitalPlatformTypeEnum.yaml

@@ -0,0 +1,168 @@
+# AuxiliaryDigitalPlatformTypeEnum - Types of secondary/subordinate digital platforms
+# 
+# Used by AuxiliaryDigitalPlatform class to classify types of secondary digital
+# properties beyond the main website/platform.
+# 
+# Generation date: 2025-11-25
+# 
+id: https://nde.nl/ontology/hc/enum/auxiliary-digital-platform-type
+name: auxiliary-digital-platform-type-enum
+title: Auxiliary Digital Platform Type Enumeration
+
+imports:
+  - linkml:types
+
+enums:
+  AuxiliaryDigitalPlatformTypeEnum:
+    description: >-
+      Types of secondary or subordinate digital platforms for heritage custodians.
+      
+      These represent digital properties beyond the main website, including project
+      sites, exhibition microsites, specialized APIs, mobile apps, etc.
+      
+      Aligns with DCAT dcat:Catalog concept for secondary data catalogs/services.
+    
+    permissible_values:
+      PROJECT_WEBSITE:
+        title: project website
+        description: >-
+          Dedicated website for a specific project, research initiative, or
+          long-term program. May have finite lifespan matching project duration.
+        meaning: dcat:Catalog
+        annotations:
+          examples: "Rijksstudio, Operation Night Watch, Digitization project portal"
+      
+      EXHIBITION_MICROSITE:
+        title: exhibition microsite
+        description: >-
+          Temporary website for specific exhibition or event. Has defined
+          valid_from/valid_to matching exhibition dates.
+        meaning: dcat:Catalog
+        annotations:
+          examples: "Temporary exhibition site, Virtual tour for exhibition, Exhibition archive"
+      
+      API_ENDPOINT:
+        title: API endpoint
+        description: >-
+          Programmatic interface separate from main API. Developer tools,
+          specialized data access, experimental APIs.
+        meaning: dcat:DataService
+        annotations:
+          examples: "Data API, IIIF API, Search API, Metadata API"
+      
+      MOBILE_APP:
+        title: mobile app
+        description: >-
+          Native or hybrid mobile application for iOS/Android. May be guide app,
+          collection browser, or interactive experience.
+        meaning: schema:MobileApplication
+        annotations:
+          examples: "Museum guide app, Collection browser app, AR experience app"
+      
+      COLLECTION_BROWSER:
+        title: collection browser
+        description: >-
+          Specialized tool for exploring specific collection or dataset.
+          Rich interface beyond main catalog search.
+        meaning: dcat:Catalog
+        annotations:
+          examples: "Paintings explorer, Photograph viewer, Interactive map"
+      
+      CROWDSOURCING_PLATFORM:
+        title: crowdsourcing platform
+        description: >-
+          Platform for user contributions: transcription, tagging, identification,
+          georeferencing, citizen science.
+        meaning: dcat:Catalog
+        annotations:
+          examples: "Transcription portal, Tagging tool, Citizen science project"
+      
+      EDUCATIONAL_PORTAL:
+        title: educational portal
+        description: >-
+          Learning resources, lesson plans, educational games, teacher materials.
+          May be separate platform or subdomain.
+        meaning: schema:LearningResource
+        annotations:
+          examples: "Teacher resources, Student portal, Educational games"
+      
+      DATA_PORTAL:
+        title: data portal
+        description: >-
+          Platform for downloading datasets, bulk exports, open data access.
+          May have different access policies than main platform.
+        meaning: dcat:Catalog
+        annotations:
+          examples: "Open data portal, Dataset downloads, Bulk export service"
+      
+      LEGACY_PLATFORM:
+        title: legacy platform
+        description: >-
+          Deprecated but maintained platform, old website version, sunset service.
+          No longer actively developed but still accessible.
+        meaning: dcat:Catalog
+        annotations:
+          examples: "Old website archive, Deprecated API version, Legacy search"
+      
+      VIRTUAL_TOUR:
+        title: virtual tour
+        description: >-
+          360-degree tours, VR experiences, immersive gallery views.
+          Interactive spatial exploration of physical spaces.
+        meaning: schema:VirtualLocation
+        annotations:
+          examples: "360° gallery tour, VR museum, Google Arts & Culture street view"
+      
+      BLOG_NEWS:
+        title: blog and news
+        description: >-
+          Blog, news section, or content marketing platform separate from
+          main website. May be on different domain or platform.
+        meaning: schema:Blog
+        annotations:
+          examples: "Institutional blog, News portal, Stories section"
+      
+      SOCIAL_MEDIA:
+        title: social media presence
+        description: >-
+          Official social media accounts and channels. Instagram, Twitter,
+          Facebook, YouTube, TikTok institutional accounts.
+        meaning: schema:SocialMediaPosting
+        annotations:
+          examples: "Instagram account, YouTube channel, Twitter/X profile"
+      
+      PODCAST_CHANNEL:
+        title: podcast channel
+        description: >-
+          Audio podcast or video series hosted on dedicated platform.
+          Spotify, Apple Podcasts, YouTube, SoundCloud.
+        meaning: schema:PodcastSeries
+        annotations:
+          examples: "Museum podcast, Archive stories, Curator talks"
+      
+      BOOKING_SYSTEM:
+        title: booking system
+        description: >-
+          Online reservation and ticketing system, may be third-party platform
+          or custom solution. Reading room appointments, event tickets.
+        meaning: schema:ReservationPackage
+        annotations:
+          examples: "Ticket booking, Reading room reservations, Tour scheduling"
+      
+      WEBSHOP:
+        title: webshop
+        description: >-
+          E-commerce platform for museum shop, print-on-demand, merchandise.
+          May be separate domain or integrated.
+        meaning: schema:OnlineStore
+        annotations:
+          examples: "Museum shop, Print shop, Publications store"
+      
+      NEWSLETTER:
+        title: newsletter platform
+        description: >-
+          Email newsletter signup and archive. Mailchimp, Campaign Monitor,
+          or institutional email marketing.
+        meaning: schema:NewsArticle
+        annotations:
+          examples: "Monthly newsletter, Exhibition announcements, Member updates"

schemas/20251121/linkml/modules/enums/AuxiliaryPlaceTypeEnum.yaml

@@ -0,0 +1,132 @@
+# AuxiliaryPlaceTypeEnum - Types of secondary/subordinate physical locations
+# 
+# Used by AuxiliaryPlace class to classify types of secondary locations
+# that heritage custodians operate at beyond their main headquarters.
+# 
+# Generation date: 2025-11-25
+# 
+id: https://nde.nl/ontology/hc/enum/auxiliary-place-type
+name: auxiliary-place-type-enum
+title: Auxiliary Place Type Enumeration
+
+imports:
+  - linkml:types
+
+enums:
+  AuxiliaryPlaceTypeEnum:
+    description: >-
+      Types of secondary or subordinate physical locations for heritage custodians.
+      
+      These represent physical sites beyond the main headquarters where custodians
+      operate, including storage facilities, branch offices, research centers, etc.
+      
+      Aligns with W3C ORG org:Site concept for organizational premises.
+    
+    permissible_values:
+      BRANCH_OFFICE:
+        title: branch office
+        description: >-
+          Regional or satellite office providing services in a different location
+          from the main headquarters. May have reading room, public services.
+        meaning: org:Site
+        annotations:
+          examples: "Noord-Hollands Archief regional reading room, University library branch campus"
+      
+      STORAGE_FACILITY:
+        title: storage facility
+        description: >-
+          Off-site storage depot, warehouse, or vault for collections. Typically
+          climate-controlled, staff-access only, not public-facing.
+        meaning: crm:E27_Site
+        annotations:
+          examples: "Rijksmuseum Depot Amersfoort, Archive document center"
+      
+      RESEARCH_CENTER:
+        title: research center
+        description: >-
+          Specialized research facility separate from main building. Conservation
+          labs, digitization centers, scholarly research units.
+        meaning: org:Site
+        annotations:
+          examples: "Conservation lab, Digitization center, Research library annex"
+      
+      EXHIBITION_SPACE:
+        title: exhibition space
+        description: >-
+          Satellite gallery or exhibition pavilion separate from main museum.
+          May be temporary or permanent installation.
+        meaning: crm:E27_Site
+        annotations:
+          examples: "Rijksmuseum Schiphol, Pop-up museum, Outdoor sculpture garden"
+      
+      HISTORIC_BUILDING:
+        title: historic building
+        description: >-
+          Secondary historic property managed by same custodian. Historic houses,
+          heritage buildings, archaeological sites.
+        meaning: crm:E27_Site
+        annotations:
+          examples: "Historic house museum annex, Heritage property, Preserved building"
+      
+      TEMPORARY_LOCATION:
+        title: temporary location
+        description: >-
+          Temporary facility during renovation, relocation, or special events.
+          Has defined valid_from/valid_to dates.
+        meaning: crm:E27_Site
+        annotations:
+          examples: "Renovation storage, Temporary exhibition venue, Event pavilion"
+      
+      ADMINISTRATIVE_OFFICE:
+        title: administrative office
+        description: >-
+          Non-public administrative building for staff operations, HR, finance,
+          IT services. Not a public-facing heritage facility.
+        meaning: org:Site
+        annotations:
+          examples: "Administrative headquarters, Back-office facility, IT data center"
+      
+      EDUCATION_CENTER:
+        title: education center
+        description: >-
+          Dedicated educational facility for workshops, classes, public programs.
+          May be at different location from main institution.
+        meaning: org:Site
+        annotations:
+          examples: "Youth education center, Teacher training facility, Workshop space"
+      
+      CONSERVATION_LAB:
+        title: conservation lab
+        description: >-
+          Specialized conservation and restoration facility with technical equipment.
+          May serve multiple institutions.
+        meaning: crm:E27_Site
+        annotations:
+          examples: "Paper conservation lab, Paintings restoration studio, Digital preservation lab"
+      
+      READING_ROOM_ANNEX:
+        title: reading room annex
+        description: >-
+          Overflow or specialized reading room separate from main building.
+          For peak periods or specialized collections.
+        meaning: org:Site
+        annotations:
+          examples: "Manuscript reading room, Genealogy research center, Microfilm reading room"
+      
+      WAREHOUSE:
+        title: warehouse
+        description: >-
+          Large-scale storage building for bulk materials, supplies, or
+          non-collection items. Industrial facility.
+        meaning: crm:E27_Site
+        annotations:
+          examples: "Equipment warehouse, Supplies storage, Exhibition materials storage"
+      
+      OUTDOOR_SITE:
+        title: outdoor site
+        description: >-
+          Open-air heritage site, garden, park, or landscape feature managed
+          by the custodian. Archaeological site, sculpture garden.
+        meaning: crm:E53_Place
+        annotations:
+          examples: "Sculpture garden, Archaeological excavation site, Historic park"

schemas/20251121/linkml/modules/enums/OrganizationBranchTypeEnum.yaml

@@ -0,0 +1,134 @@
+# OrganizationBranchTypeEnum - Types of formal organizational branches
+# 
+# Used by OrganizationBranch class to classify types of formal sub-organizations
+# that operate at auxiliary physical locations.
+# 
+# Generation date: 2025-11-25
+# 
+id: https://nde.nl/ontology/hc/enum/organization-branch-type
+name: organization-branch-type-enum
+title: Organization Branch Type Enumeration
+
+imports:
+  - linkml:types
+
+enums:
+  OrganizationBranchTypeEnum:
+    description: >-
+      Types of formal organizational branches for heritage custodians.
+      
+      These represent formal sub-organizations that operate at physical sites,
+      with some degree of administrative autonomy (own staff, budget, services).
+      
+      Distinguished from OrganizationalStructure (informal units like departments/teams).
+      
+      Aligns with W3C ORG org:OrganizationalUnit concept.
+    
+    permissible_values:
+      REGIONAL_OFFICE:
+        title: regional office
+        description: >-
+          Geographic regional branch serving a specific area. Full service branch
+          with own staff, reading room, and public services.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Regionaal Historisch Centrum Noord-Holland, State Library branch"
+      
+      BRANCH_LIBRARY:
+        title: branch library
+        description: >-
+          Library branch at satellite campus, district, or specialized location.
+          Own collection, staff, and services.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Science Library, Medical Library, Community Library branch"
+      
+      SATELLITE_GALLERY:
+        title: satellite gallery
+        description: >-
+          Museum exhibition space at separate location. Own curatorial program,
+          exhibitions, possibly specialized collection focus.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Modern Art Annex, Contemporary Gallery, Airport exhibition space"
+      
+      CONSERVATION_LAB:
+        title: conservation lab
+        description: >-
+          Formal conservation/restoration unit with specialized staff.
+          May serve multiple institutions, semi-autonomous operations.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Conservation Division, Restoration Center, Preservation Lab"
+      
+      DIGITIZATION_CENTER:
+        title: digitization center
+        description: >-
+          Dedicated digital production facility for scanning, photography,
+          digital preservation. Technical staff and equipment.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Digital Production Center, Imaging Lab, Audiovisual Digitization"
+      
+      RESEARCH_CENTER:
+        title: research center
+        description: >-
+          Formal research unit focused on scholarly activities, publications,
+          academic programs. May have own research staff.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Research Institute, Documentation Center, Study Center"
+      
+      EDUCATION_CENTER:
+        title: education center
+        description: >-
+          Formal educational program unit for public education, school programs,
+          teacher training. Own education staff.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Education Department, Public Programs, Outreach Center"
+      
+      ADMINISTRATIVE_OFFICE:
+        title: administrative office
+        description: >-
+          Central administration unit handling HR, finance, IT, facilities.
+          Not public-facing, staff operations only.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Central Administration, Shared Services, Operations Center"
+      
+      STORAGE_MANAGEMENT:
+        title: storage management
+        description: >-
+          Formal unit managing off-site storage facilities, logistics,
+          collection movement, climate control.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Collection Storage Operations, Depot Management, Logistics Unit"
+      
+      EXHIBITION_SPACE:
+        title: exhibition space
+        description: >-
+          Formal exhibition programming unit, may be temporary or permanent.
+          Separate from main museum galleries.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Special Exhibitions, Traveling Exhibitions, Project Space"
+      
+      VISITOR_SERVICES:
+        title: visitor services
+        description: >-
+          Public-facing unit at auxiliary location handling visitors,
+          ticketing, tours, accessibility.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Visitor Center, Welcome Center, Tour Operations"
+      
+      COLLECTIONS_CENTER:
+        title: collections center
+        description: >-
+          Centralized collections management unit, possibly serving multiple
+          institutions. Registration, cataloging, loans.
+        meaning: org:OrganizationalUnit
+        annotations:
+          examples: "Collections Management Center, Registrar Services, Loans Department"

schemas/20251121/linkml/modules/slots/auxiliary_places.yaml

@@ -0,0 +1,98 @@
+# Auxiliary Places Slot
+# Links CustodianPlace to subordinate/secondary physical locations
+# W3C Org: org:hasSite pattern for organizational sites
+
+id: https://nde.nl/ontology/hc/slot/auxiliary_places
+name: auxiliary_places
+
+prefixes:
+  linkml: https://w3id.org/linkml/
+  hc: https://nde.nl/ontology/hc/
+  org: http://www.w3.org/ns/org#
+  schema: http://schema.org/
+
+imports:
+  - linkml:types
+
+slots:
+  auxiliary_places:
+    slot_uri: org:hasSite
+    range: AuxiliaryPlace
+    multivalued: true
+    inlined_as_list: true
+    description: >-
+      Subordinate or secondary physical locations associated with this CustodianPlace.
+      
+      **W3C ORG Alignment**:
+      
+      `org:hasSite` - "Indicates a site at which the Organization has some presence 
+      even if only indirect (e.g. virtual office or a professional service 
+      which is acting as the registered address for a company)."
+      
+      **Hierarchical Pattern**:
+      
+      CustodianPlace (main headquarters)
+        └── auxiliary_places → AuxiliaryPlace[] (subordinate sites)
+            └── hosts_branch → OrganizationBranch (formal branch at site)
+      
+      This mirrors the CustodianName → CustodianAppellation pattern:
+      - CustodianName is preferred name (skos:prefLabel)
+      - CustodianAppellation is alternative name (skos:altLabel)
+      - CustodianPlace is main place (org:Site - primary)
+      - AuxiliaryPlace is subordinate place (org:Site - secondary)
+      
+      **Use Cases**:
+      
+      1. **Off-site Storage**:
+         - Museum depot in another city
+         - Archive annex for overflow documents
+      
+      2. **Branch Locations**:
+         - Regional library branches
+         - Satellite museum galleries
+      
+      3. **Specialized Facilities**:
+         - Conservation lab in separate building
+         - Digitization center at different address
+      
+      4. **Temporary Locations**:
+         - Exhibition pavilions
+         - Storage during renovation
+      
+      **Example - Rijksmuseum**:
+      ```yaml
+      CustodianPlace:
+        place_name: "Rijksmuseum"
+        place_specificity: BUILDING
+        auxiliary_places:
+          - place_name: "Depot Amersfoort"
+            auxiliary_place_type: STORAGE_FACILITY
+          - place_name: "Rijksmuseum Schiphol"
+            auxiliary_place_type: BRANCH_OFFICE
+            hosts_branch:
+              branch_name: "Schiphol Exhibition Team"
+      ```
+      
+      **Temporal Considerations**:
+      
+      Auxiliary places have independent lifecycles:
+      - Storage facility opened 1995, closed 2010
+      - Branch office valid_from 2000, still active
+      
+      Each AuxiliaryPlace tracks its own valid_from/valid_to dates.
+      
+      **Query Pattern**:
+      
+      "Find all locations of Rijksmuseum":
+      - Main: CustodianPlace.place_name
+      - Secondary: CustodianPlace.auxiliary_places[*].place_name
+    examples:
+      - value:
+          - place_name: "Depot Amersfoort"
+            auxiliary_place_type: STORAGE_FACILITY
+            street_address: "Euterpelaan 25"
+            city: "Amersfoort"
+          - place_name: "Rijksmuseum Schiphol"
+            auxiliary_place_type: BRANCH_OFFICE
+            street_address: "Schiphol Airport, Lounge 2"
+        description: "Rijksmuseum subordinate locations"

schemas/20251121/linkml/modules/slots/auxiliary_platforms.yaml

@@ -0,0 +1,110 @@
+# Auxiliary Platforms Slot
+# Links DigitalPlatform to subordinate/project-based digital properties
+# DCAT: dcterms:hasPart pattern for data catalogs
+
+id: https://nde.nl/ontology/hc/slot/auxiliary_platforms
+name: auxiliary_platforms
+
+prefixes:
+  linkml: https://w3id.org/linkml/
+  hc: https://nde.nl/ontology/hc/
+  dcat: http://www.w3.org/ns/dcat#
+  dcterms: http://purl.org/dc/terms/
+
+imports:
+  - linkml:types
+
+slots:
+  auxiliary_platforms:
+    slot_uri: dcterms:hasPart
+    range: AuxiliaryDigitalPlatform
+    multivalued: true
+    inlined_as_list: true
+    description: >-
+      Subordinate or project-based digital platforms associated with this DigitalPlatform.
+      
+      **DCAT Alignment**:
+      
+      `dcterms:hasPart` - "A related resource that is included either physically 
+      or logically in the described resource."
+      
+      Used in DCAT for catalog → sub-catalog relationships.
+      
+      **Hierarchical Pattern**:
+      
+      DigitalPlatform (main digital entry point)
+        └── auxiliary_platforms → AuxiliaryDigitalPlatform[] (project sites)
+      
+      This mirrors the CustodianName → CustodianAppellation pattern:
+      - CustodianName is preferred label (skos:prefLabel)
+      - CustodianAppellation is alternative name (skos:altLabel)
+      - DigitalPlatform is main digital entry (foaf:homepage)
+      - AuxiliaryDigitalPlatform is subordinate platform (dcterms:hasPart)
+      
+      **Use Cases**:
+      
+      1. **Project Websites**:
+         - Research project portals
+         - Grant-funded digitization sites
+      
+      2. **Exhibition Microsites**:
+         - Temporary exhibition with dedicated website
+         - Virtual tours for specific collections
+      
+      3. **APIs and Tools**:
+         - Developer APIs (separate from main website)
+         - Collection browser tools
+         - Mobile applications
+      
+      4. **Legacy/Archived Platforms**:
+         - Previous website versions
+         - Deprecated systems still accessible
+      
+      5. **Educational Portals**:
+         - Teacher resources
+         - Student learning modules
+      
+      **Example - Rijksmuseum**:
+      ```yaml
+      DigitalPlatform:
+        platform_name: "Rijksmuseum Website"
+        homepage_web_address: "https://www.rijksmuseum.nl/"
+        auxiliary_platforms:
+          - platform_name: "Rijksstudio"
+            auxiliary_platform_type: PROJECT_WEBSITE
+            platform_url: "https://www.rijksmuseum.nl/nl/rijksstudio"
+          - platform_name: "Rijksmuseum Data API"
+            auxiliary_platform_type: API_ENDPOINT
+            platform_url: "https://data.rijksmuseum.nl/"
+          - platform_name: "Night Watch Experience"
+            auxiliary_platform_type: EXHIBITION_MICROSITE
+            platform_url: "https://www.rijksmuseum.nl/en/stories/operation-night-watch"
+      ```
+      
+      **Temporal Considerations**:
+      
+      Auxiliary platforms often have finite lifespans:
+      - Exhibition microsite: opens/closes with exhibition
+      - Project portal: funded period only
+      - Legacy platforms: archived but not deleted
+      
+      Each AuxiliaryDigitalPlatform tracks:
+      - valid_from/valid_to: exact dates
+      - archival_status: ACTIVE/DEPRECATED/ARCHIVED/OFFLINE
+      - archived_at: Wayback Machine URL if archived
+      
+      **Query Pattern**:
+      
+      "Find all digital properties of Rijksmuseum":
+      - Main: DigitalPlatform.homepage_web_address
+      - Secondary: DigitalPlatform.auxiliary_platforms[*].platform_url
+    examples:
+      - value:
+          - platform_name: "Rijksstudio"
+            auxiliary_platform_type: PROJECT_WEBSITE
+            platform_url: "https://www.rijksmuseum.nl/nl/rijksstudio"
+            archival_status: "ACTIVE"
+          - platform_name: "Rijksmuseum Data API"
+            auxiliary_platform_type: API_ENDPOINT
+            platform_url: "https://data.rijksmuseum.nl/"
+        description: "Rijksmuseum subordinate digital platforms"

schemas/20251121/linkml/modules/slots/located_at.yaml

@@ -0,0 +1,82 @@
+# Located At Slot
+# Links OrganizationalStructure to a physical location (AuxiliaryPlace)
+# W3C Org: org:basedAt pattern for organization locations
+
+id: https://nde.nl/ontology/hc/slot/located_at
+name: located_at_slot
+
+prefixes:
+  linkml: https://w3id.org/linkml/
+  hc: https://nde.nl/ontology/hc/
+  org: http://www.w3.org/ns/org#
+  schema: http://schema.org/
+
+imports:
+  - linkml:types
+
+slots:
+  located_at:
+    slot_uri: org:basedAt
+    range: AuxiliaryPlace
+    multivalued: true
+    inlined_as_list: true
+    description: >-
+      Physical location (AuxiliaryPlace) where this organizational unit operates.
+      
+      **W3C ORG Alignment**:
+      
+      `org:basedAt` - "Indicates the site at which the Organization has its main 
+      administrative/operational presence."
+      
+      Alternative: `org:hasSite` - "Indicates a site at which the Organization 
+      has some presence even if only indirect."
+      
+      **Use Cases**:
+      
+      1. **Departments at Branch Locations**:
+         - Conservation Team → located at Amersfoort Depot
+         - Digitization Team → located at off-site facility
+      
+      2. **Teams Spanning Multiple Locations**:
+         - IT Department → located at main building AND data center
+         - Public Services → located at main reading room AND annex
+      
+      3. **Temporary Location Assignments**:
+         - Exhibition Team → temporarily at partner venue
+         - Collections → temporarily at storage during renovation
+      
+      **Relationship Pattern**:
+      
+      Two-way linking between locations and organizational units:
+      
+      ```
+      AuxiliaryPlace
+        └── hosts_branch → OrganizationBranch
+            └── has_operational_unit → OrganizationalStructure
+      
+      OrganizationalStructure
+        └── located_at → AuxiliaryPlace (optional)
+      ```
+      
+      **Optional Slot**:
+      
+      Many organizational units don't have fixed locations:
+      - Strategic Planning Committee (meets virtually)
+      - Research Fellowship Program (no physical space)
+      
+      Only use when organizational unit has identifiable physical location.
+      
+      **Example - Conservation Division**:
+      ```yaml
+      OrganizationalStructure:
+        unit_name: "Conservation Division"
+        unit_type: DIVISION
+        located_at:
+          - place_name: "Conservation Lab - Main Building"
+          - place_name: "Climate-Controlled Storage - Depot Amersfoort"
+      ```
+    examples:
+      - value:
+          - place_name: "Depot Amersfoort"
+            auxiliary_place_type: STORAGE_FACILITY
+        description: "Organizational unit located at off-site storage"