This document addresses the nature and value of ‘an Interaction Style Guide (ISG)’ as a key element in the development and implementation of the direct manipulation graphical interfaces, which are starting to be introduced into operational centres. It identifies the structure and contents appropriate to such a guide, and demonstrates these with the guidance material corresponding to the ‘Example’ Human-Machine Interface produced to test and illustrate the CoRe development processes. The document contains a large number of hyperlinks and is best used in an electronic form.