# Category 4: Data

> **Usage:** Definition of entities and data rules
> **When to load:** If feature is data-centric or full module

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## 4.1 Entities

| # | Question | Answer Type |
|---|----------|-------------|
| Q4.1 | What are the main entities handled? | List |
| Q4.2 | For each entity: important attributes? | Per entity |
| Q4.3 | What relationships exist between entities? | Text schema |
| Q4.4 | Expected data volume? | Estimation |

## 4.2 Data Rules

| # | Question | Answer Type |
|---|----------|-------------|
| Q4.5 | What validations on data? | List of rules |
| Q4.6 | Which fields are required vs optional? | Per field |
| Q4.7 | What specific formats/constraints? | List |
| Q4.8 | Sensitive data to protect? | List + level |

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## SmartStack Mapping

| Business Concept | SmartStack |
|-----------------|------------|
| Main entity | Domain Entity |
| Required attribute | `[Required]` |
| Unique attribute | `HasIndex().IsUnique()` |
| 1:N relationship | Navigation property |
| Sensitive data | Encryption + audit |
