A computer-implemented method for creating a hierarchical block diagram in a graphical development environment includes: automatically creating a hierarchical black box for a respective further subsystem block. The hierarchical black box is configured to resolve a corresponding hierarchical level when selected by a user. The automatic creation is carried out via a callback function. The hierarchical black box has the following features: at least one interface description and/or graphical representation of the inputs/outputs of the respective further subsystem block in its hierarchical level, which the respective further subsystem block previously also occupied; at least one reference to model content for the respective further subsystem block, comprising further black boxes for the further subsystem blocks in the subordinate hierarchical levels; parameters that the respective further subsystem block previously also had; and generated source code of the respective further subsystem block.