关于“Hardware Design Guide for KeyStone I Devices”文档中的一个问题请教一下。

文档第77页对未使用的SPI引脚的要求有一个注释，如下：

Note—*: The above recommendations are based on the peripheral being
unused and no traces attached. If traces are attached to any of the peripheral
input pins, added pull-up (to DVDD18) or pull-down (to VSS) resistors
(4.7 k) are needed.

这段文字怎么解释？尤其是“traces are attached to any of the peripheral input pins” 是什么意思？

谢谢！