MathObjects are highly customizable: Can add/remove operators, functions, variables, constants, etc. e.g., represent $\tan(x)$ in terms of $\sin(x)$ and $\cos(x)$ without access to $\tan(x)$. Can create new object types e.g., scientific notation, inequalities, polynomials, currency, chemical reactions Can create custom checkers e.g., formula up to constant, implicit planes, parametric lines