Finally, when performing synthesis, whether manually or automated, we are dealing with more than abstract substances, in fact, the chemistry hardware does not really know or care about molecular structures, but they do very much care about the form and other characteristics of the actual material used for the reactants. E.g., is it a powder, and if yes, how fine? Is it a liquid? What is its viscosity? How should substances be mixed or added together given their properties? What is their solubility in different solvents? What can we used to wash our vessels? Some of these considerations are included in XDL already, but since XDL is designed for a type of reaction apparatus which carries most reagents as liquids, either a fluid or a suspension through pipes, pumps, and valves, it is limited in this regard.