Abstract
The present paper is a sequel to papers dealing with recent developments on the issue of `quantum measurement'. In this paper `measurement within the domain of application of quantum mechanics' is treated as a \emph{quantum mechanical} \emph{interaction} of a `(sub)microscopic object (o)' and an `equally (sub)microscopic part of the measuring instrument (a) being sensitive to the (sub)microscopic information', that interaction to be described by a Schr\"odinger equation. The Stern-Gerlach experiment is used as a paradigmatic example. An alternative to the Heisenberg inequality is found, exhibiting the \emph{independent} contributions of `preparation of the initial state of object (o)' \emph{and} `interaction of object (o) \emph{and} measuring instrument/probe (a)'. Applicability of the Liouville-von Neumann equation is stressed.