It is important to specify whether a molecule may move freely through all containers of a model, which is the default setting, or if it is stationary, i.e., it is immobilized in the current container. In the latter case, for example, the molecule may represent a membrane-bound receptor protein. Non-stationary molecules imported from PK-Sim® projects are automatically associated with their distribution calculation method (e.g., PK-Sim® standard, Rodgers and Rowland, etc.) which describes the basic ADME properties of a compound. Enzymes, metabolizing processes and transporters imported from PK-Sim® projects can be found in the Molecules building block as stationary molecules.