求解“次级供应商”定义具体指的什么？

这些是我们的下游客户发过来的审核表，它这里的“次级供应商”指的什么？
是否只有合格的次级供应商才会被批准向客户供应物料？
Are only approved subtier supplier allowed to supply material to customer?
次级供应商的认证是否基于品质系统审核和过程质量分析？
Is subtier supplier qualification done base on quality system audit and process quality analysis?
次级供应商的选择是否基于有能力满足要求，包括品质要求？
Are subtier suppliers selected on the basis of their ability to meet subcontract requirements, including quality requirements?
次级供应商批准资料有没有根据定义的保存期限得到适当的保存？
Are the records for subtier suppliers approval properly maintained and kept according to the defined retention period?
供应商是否确保次级供应商的品质系统的有效性，包括对于任何不满足目标的情况进行闭环改善？
Does the supplier ensure that the subcontractors' quality system controls are effective, which includes CLCA for any out of goal situation?
是否有流程对次级零部件进行承认，例如PPAP？
Is there a procedure for sub-component approval, such as PPAP?