In the S-57 standard, entities in the real world are expressed in the form of sets of descriptive attributes and spatial attributes, and the sets of the two attributes are defined as characteristic objects and spatial objects. Attribute object refers to the entity in the real world, including the type, nature and characteristics of the entity. Spatial objects are used to describe the shape and Position Info of entities in the real world. The object we often say in the chart refers to a kind of entity composed of a unique characteristic object and multiple spatial objects, and the object must be based on the characteristic object.

The current S-57 standard only specifies the Encode Type of object data in the ocean, but lacks the Encode Type of object data in military maps and river maps. Therefore, it is necessary to provide the Extend Feature function to extend the unique Object Type of military maps and river maps.

In the SuperMap iMaritimeEditor, the Chart Data extension includes:

• S- 57 Extend Feature : Adds a new object or object attribute type to the system.
• S-52 display extension : Adds a display rule for a new object or object attribute.