问：CLK signal frequency error和required accuracy的区别

大帅哥1989

在UTMI的spec在中有这样几句话让我醉了：
2) The CLK signal frequency error must be less than 10% (±6.00 MHz)
3) The CLK must fully meet the required accuracy of ±500 ppm (±30.0 KHz), no later than 1.4ms after the
first transition of CLK.
请问这两点分别是啥？咋看上去像是一个东西呢，但是数值又不一样