View source for ICT:Conceptual Mermaid Diagram v 4.0

= Conceptual ER Diagram =

This page presents the conceptual Entity–Relationship (ER) diagram of the Costasano Heritage Database.

It visualizes the domain model independently of technical implementation details.

The diagram is intended for:

* conceptual understanding
* onboarding new contributors
* design discussions
* documentation
* validation of modeling decisions

It is not a database schema diagram.



== Scope ==

This diagram shows:

* core entities
* conceptual responsibilities
* main relationships
* hierarchies

It deliberately omits:

* junction tables
* lookup tables
* Cargo/MediaWiki mechanics
* technical fields
* optimization structures

These belong to the logical DBML schema, not the conceptual model.

See:

[[ICT:Data Model – DBML Schema]]



== Reading guide ==

=== Entities ===

Boxes represent conceptual entities:

* HeritageObject — subject of study
* Person — individual actor
* Organization — collective actor
* Place — spatial location
* DigitalAsset — interpretation of a file
* File — storage only
* ResearchChapter — narrative structure



=== Relationship conventions ===

{| class="wikitable"
! Symbol !! Meaning
|-
| ||--|| || exactly one
|-
| ||--o{ || one-to-many
|-
| }o--o{ || many-to-many
|}

Labels describe the conceptual meaning of the relationship, not database mechanics.



== Diagram ==

<mermaid>
erDiagram

    %% ========================
    %% CORE ENTITIES
    %% ========================

    HERITAGE_OBJECT {
        id
        title
        description
        date_from
        date_to
    }

    PERSON {
        id
        firstname
        lastname
    }

    ORGANIZATION {
        id
        name
    }

    PLACE {
        id
        name
        type
    }

    DIGITAL_ASSET {
        id
        description
        citation
    }

    FILE {
        id
        filename
    }

    RESEARCH_CHAPTER {
        id
        title
    }



    %% ========================
    %% CONCEPTUAL RELATIONSHIPS
    %% ========================

    %% documentation
    HERITAGE_OBJECT }o--o{ DIGITAL_ASSET : documented_by
    PERSON }o--o{ DIGITAL_ASSET : documented_by
    ORGANIZATION }o--o{ DIGITAL_ASSET : documented_by

    %% participation / roles
    HERITAGE_OBJECT }o--o{ PERSON : involves
    HERITAGE_OBJECT }o--o{ ORGANIZATION : involves
    PERSON }o--o{ ORGANIZATION : member_of

    %% spatial context
    HERITAGE_OBJECT }o--|| PLACE : located_in
    ORGANIZATION }o--|| PLACE : located_in
    DIGITAL_ASSET }o--o| PLACE : spatial_context

    %% narrative structure
    HERITAGE_OBJECT }o--o{ RESEARCH_CHAPTER : interpreted_in

    %% storage boundary
    DIGITAL_ASSET ||--|| FILE : interprets

    %% hierarchies
    HERITAGE_OBJECT ||--o{ HERITAGE_OBJECT : parent_of
    DIGITAL_ASSET ||--o{ DIGITAL_ASSET : derived_from
    RESEARCH_CHAPTER ||--o{ RESEARCH_CHAPTER : parent_of
    PLACE ||--o{ PLACE : parent_of
</mermaid>



== Design notes ==

=== Separation of concerns ===

The diagram emphasizes strict responsibility boundaries:

* Files store data
* DigitalAssets interpret files
* Persons and Organizations act
* Places locate
* HeritageObjects represent subjects
* ResearchChapters structure interpretation

No entity should cross these boundaries.



=== Technology independence ===

This diagram must remain valid even if:

* Cargo is replaced
* MediaWiki is replaced
* the database changes

If the diagram requires technical constructs to explain relationships, the model is too implementation-driven.



== Maintenance rule ==

Whenever the conceptual meaning of entities or relationships changes:

# update Entity Definitions first
# update this diagram
# then update DBML/schema

Never modify the schema without updating the conceptual layer.



== Status ==

Conceptual ER Diagram – Version 4.0