The dominant role in the graphical legend creation is played by the teacher more often than when using verbal materials. Therefore the choice of a specific reference language is connected with the concrete group of people - a class, a family etc. This feature of a graphical reference language can be the source of solvers' difficulties. The impulse for the legend creation goes out from the solver's internal need to visualise the problem structure. Iconic legends consist of real shape record.
Symbolic legends keep the structural similarity only.
Most students used the reference language consisting of both, iconic and symbolic elements. In graphical legends reference language, the symbols used are not always pure pictographic ones. During the legend creation, the solver discovers the problem structure and corresponding mathematisation. Not all these stages are necessarily recorded in the graphical legend. The solver did not find any relationship of a piece of information and the problem structure.