$\newcommand{\Dev}{\operatorname{Dev}}$ $\newcommand{\dev}{\operatorname{dev}}$ $\newcommand{\grad}{\operatorname{grad}}$ $\newcommand{\divg}{\operatorname{div}}$ $\newcommand{\Ei}{\operatorname{Ei}}$ $\newcommand{\tr}{\operatorname{tr}}$

Many model parameters can be made dependent on the reference coordinates. This is useful, for instance, for defining inhomogeneous materials. There are two mechanisms for creating heterogeneous parameters: a mathematical expression, or a map. The type of the parameter is set via the type attribute, which can take on two values.