\st[h,k]=((I+iC) \,C_0^{\half}T_{\s} \,h , C_0^{\half}T_{\s}\, k),  \quad h,k \in \dom \st= \dom T,$$ is closed and sectorial with vertex at the origin and semi-angle $\gamma \leq \arctan \|C\|$. Moreover, the maximal sectorial relation $H$ corresponding to the form $\st$ is given by $$\label{