The focus of this thesis is obtaining useful segments of historic data from normal operation due to, for instance, economical and safety concerns of performing experiments on a plant. This will be done by development, and implementation of a user friendly concept. The concept will give the user a collection of search criteria to choose from, and the ability to combine them, to locate possible informative data in historic data. The angle of attack will be more practical than theoretical.The concept SHDMI is proposed as such a tool. As a prototype of the concept it shows promise dealing with both SISO- and MIMO-systems in its simplicity and structure, but it is concluded that improvements and/or expansions of SHDMI is needed if it is to become a reliable and adequate for its purposes.