Let $\iota:K\hookrightarrow L\cong K(x)$ be a simple transcendental extension of valued fields, where $K$ is equipped with valuation $\nu$ rank 1. That is, we assume given 1 and its $\nu'$ to $L$. $(R_\nu,M_\nu,k_\nu)$ denote the ring $\nu$. The purpose this paper present refined version MacLane's theory key polynomials, similar those considered by M. Vaqui\'e, reminiscent related objects studi...