They basically call every Sibe ever agouti. And while that may be technically true, the color inheritance in Sibes is defined, and set on a scale. It's like adding creamer to your coffee. One dose lightens a little, two doses lighten a lot. Thus the difference between Black, dilute black, and grey. Difference between Wolf Grey, light grey, and silver. So on so forth. All colors are banded except dominant black and dominant black + bb, which is liver.
Their theory on the whole idea of colors in Sibes is completely backwards and makes no sense. And if they are going to call one a Wolf Grey, at least get a dog that is ACTUALLY wolf grey...and not Silver.
ETA: Regardless, that's all off topic.
So, obligatory on-topic comment is that Sibe's white coloring works a lot like creeping tan. Only it's creeping white. It's why a lot of pups lose their face masks over time.