In the S-57 specification, relation defines logical links between different data elements (such as features and geometries) in the chart data model. These relationships can be spatial relationships (e.g., topology) or non-spatial relationships (e.g., logical connections between features). Relations are implemented through pointers in data structures, where pointers contain foreign keys to establish one-directional associations between records.

Feature association rules are critical in S-57 standards, categorized into aggregation and master-slave types:

• Aggregation: Logical groupings of multiple features, typically describing scenarios where multiple features act as a unified entity.
  • Aggregated Feature
    • A light buoy group (combination of multiple buoys) is considered as a single navigational auxiliary function.
    • Multiple fairways form a route network.
  • Associated Feature
    • Association between a bridge feature and its navigation restrictions (e.g., clearance height).
    • Functional linkage between a port and its anchorage areas.
• Master-Slave: Hierarchical and dependent relationships where one feature (master) controls or contains another (slave). For example, a light buoy acts as the master, while its topmark, light characteristics, and fog signals are slave features.
  • Master feature: Plays the dominant role in defining the relationship.
  • Slave feature: Subordinate to the master, supplementing its functionality or attributes.

In chart data processing, relationship management is crucial for ensuring structured, standardized, and efficient data applications. By defining logical connections between features, it enhances data organization and supports complex chart production and navigation applications. These relationships also provide foundations for subsequent standards (e.g., S-101), ensuring sustainable development of chart data models.

This section covers:

• Create Aggregation: Explains defining collection/association relationships through attribute tables to organize logical connections between chart features without requiring spatial information.
• Create Master-Slave: Describes defining hierarchical chart feature relationships by specifying master and slave features to improve data management and representation accuracy.
• Build Master-slave Relationships in Batches: Demonstrates efficiently establishing bulk master-slave relationships through coordinate matching to ensure data consistency and accuracy.
• Modify Relationships: Explains adjusting reference objects in collections or reassigning master-slave dependencies to maintain relationship precision.