Constraints: While facts describe relationships between types within the business domain, constraints describe limitations in that domain.

约束：事实描述业务领域中不同类型之间的关系，而约束(constraints)则描述那个领域中的限制。

youdao

Describes how to view the inheritance relationships between types.

说明如何检视型别之间的继承关系。

youdao

"There are several robust sites around, but we like the flexibility XTF gives us in presenting data and uncovering relationships between different types of ETFs, " Mr. Colas says.

WSJ: Best Websites for Screening ETFs

However, as petrol and diesel engines are also improving, the relationships between the different types of vehicles are not constant.

BBC: Electric cars 'pose environmental threat'