说明了内容、元数据和基础类型之间的属性和关系。

It illustrates the properties and relationships among the content, metadata, and base types.

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基础类型定义所有其他类型从中扩展的核心类型，并提供内容支持的所有通用属性。

Base types define the core types from which all other types extend, and provide all common properties that the content will support.

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元数据类型是特定内容类型与基础类型聚合的类型，提供特定于某类内容的特定属性。

Metadata types are those that specific content types aggregate with the base types to provide specific, well-known properties that are specific to a type of content.

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