The grouping system used here follows closely grouping systems common to engineering. Slight difference exist in other grouping systems.

这里所用的分类体系类似于工程上的常用的分类体系，仅仅存在细微的差别。

youdao

With a grouping system, you can save yourself the trouble of trying to remember or name all the people in a particular group.

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It's a question that one academic grouping, the Earth System Governance Project, has spent a decade researching.

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