This definition is used to multiply or divide quantities to produce a product or quotient. There are two quantities with a choice of whether to multiply or divide them.
Formever maintains unit consistency. This means that dimensionality must make sense. So a rate like $/hour can be multiplied by something with a dimensionality of time (duration). Similarly a currency amount can be divided by a duration amount to produce a rate. However, for example, a currency amount cannot be multiplied by another currency amount as that makes no sense from a dimensionality viewpoint. Dimensionless quantities (like dozens or units) can multiply or divide any quantity.
Part of this definition is specifying the result type. It must agree in dimensionality with the resulting products and quotients that are produced by the multiplication or division.
Formever will automatically convert each of the products or quotients into the specified result type.
For example, a quantity of acres could be multiplied by a dimensionless quantity to produce a result in square feet.