![Information Techologies for Security](https://it4sec.org/sites/default/files/it4sec_banner_0.png)
<p>Conceptual modelling is one of the most challenging parts in simulation modelling where more knowledge fields meet each other. The main goal of the paper is to present the process of creating a conceptual model as an important step in simulation model development. The starting point is a description of a real entity given by subject matter expert, and output is one consistent, algorithm-like, conceptual model. As a real entity here is used a process of field maintenance of main weapon system in a brigade-size military unit in combat operations. The point of the paper is to emphasize the translation of the conceptual description of the real process given from the subject matter expert, towards a formalized conceptual model that is understandable to the simulation modeller and computer programmer.</p>