Subtypes

In geodatabases, a subset of features in a feature class or objects in a table that share the same attributes.

分享相同的属性

For example, the streets in a streets feature class could be categorized into three subtypes: local streets, collector streets, and arterial streets.

比如一个街道可以分成三个子类型

Creating subtypes can be more efficient than creating many feature classes or tables in a geodatabase.

建立子类比建立许多要素类或表更有效

 For example, a geodatabase with a dozen feature classes that have subtypes will perform better than a geodatabase with a hundred feature classes.

Subtypes also make editing data faster and more accurate because default attribute values and domains can be set up.

通过使用默认的属性值和域，子类可以使编辑数据更快更正确

For example, a Local Street subtype could be created and defined so that whenever this type of street is added to the feature class, its speed limit attribute is automatically set to 35 miles per hour. 

例如，一个street subtype可以被创建和定义

无论何时这种类型的street被添加到feature class中，它的速度限制都自动设为35千米每小时