EHCI协议求助

我最近在看EHCI Specifications,小弟不是学相关专业的，看到the auxiliary well和the core well不明白是什么意思，哪位大虾给解释一下，感激不尽！原文如下：
Registers in the auxiliary well are reset under different conditions than the registers in the core well. The
auxiliary well, memory-space registers are initialized to their default values in the following cases:
• initial power-up of the auxiliary power well, or
• a value of 1b in HCReset
The core well, memory-space registers are initialized to their default values in the following cases:
• assertion of the system (core-well) hardware reset, or
• a value of 1b in HCReset, or
• transition from the PCI Power Management D3hot state to the D0 state
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