Name for $d$ in the equation $\mathbf{r}\cdot\mathbf{n}=d$ that describes a plane

Question

We can describe a plane by $$\mathbf{r}\cdot\mathbf{n}=d,$$ where $\mathbf{n}$ is the plane's normal vector and $d$ is a constant.

Is there an even somewhat-standard name for the constant $d$?