# Conceptual ERD


```mermaid
erDiagram
    Session ||--o| Task : "has 0..1"
    Session }o--o{ NormArticle : "has 0..n"
    Task ||--o| FormValues : "has 0..1"
    Task ||--o| Document : "has 0..1"
    Document }o--o{ NormArticle : "references n..n"
    Document ||--|{ DocVersion : "has 1..n"
```
- A Session can cover zero or more NormArticles
- A Session can have one or zero tasks to complete
- The Task can be to fill in one or more values in a Form. The values are stored for later retrieval.
- The Task can be to upload a Document. The Document is stored for later retrieval.
- If a new version of a Document is uploaded, a new DocVersion is created.
- A Document is **proof for** one or more NormArticles (ISO 27001 Controls or Chapters)
- A NormArticle is **proven by** one or more documents