From the mid-nineties, a new path for automatically generating UML conceptual schemas from controlled languages, by means of heuristic rules, has been proposed. This path still exhibit problems to be solved: ambiguity of heuristic rules, semi-automated expert-participation processes, difficulties in representing structural and dynamic features of the domain, focus on only one diagram, and lack of implementation. In this paper, we employ the so-called Pre-conceptual Schemas as a graphical language for representing the domain of a software application; also, we implement in the C# language the conversion rules from Pre-conceptual Schemas into UML 2.0 diagrams. C# implementation avoids ambiguity of some of the conversion rules; furthermore, C# implementation permits process automation without the need of experts. Finally, we show the functionality of C# rule-based prototype by means of a case study.
