They provide further clarification if the high-level namespace isn't enough to establish context for the PHP class you're creating.

当顶级名称空间还不足以为php类建立上下文时，它们提供进一步说明。

youdao

Shafi thought it would be useful if companies were able to establish relationships with high potential people below that top executive tier.

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Last month she lost a High Court action that sought to establish her partner's legal right to help her die if and when she chooses.

BBC: Europe