这是因为实际的源代码和变量绑定可以更改，这是建立在环境或者构建宏预处理程序指令的时间定义的基础上的。

This is because the actual source code and the variable binding can change, based on the environment or the build time definitions of macros and preprocessor commands.

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然后，它存储一个对PDOM中的单元文件的引用以及对所包含的指令和宏定义的其他引用。

Then, it stores a reference to the unit's file in the PDOM, along with references to the included directives and macro definitions.

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在宏加工系统中，建立由宏指令生成的指令格式的那部分宏定义。

In macro process system , that part of macrodefinition which forms instruction format generated by the macroinstruction.

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