Use a double IDREF relationship.

使用单一idref关系。

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We model these ID and IDREF attributes in SDO with noncontainment references.

我们使用非包容引用建模 SDO 中的 ID 和 IDREF 属性。

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If the information is required to be in a standard DTD-like attribute type such as ID, IDREF, or ENTITY, use an attribute.

如果信息需要作为类似标准DTD的属性类型，如ID、IDREF或ENTITY，则使用属性。

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