Derived   A value of derived indicated by a forward slash (/) either prefixing the name or in isolation, indicates that the association end is derived. This means that its value can be calculated from other properties of the instance.

Explanation

The forward slash indicates that the value can be calculated from other properties of the instance. This is an important concept and if modeled correctly can prevent errors in a running system that result from unintentional redundancy. We see many examples of this in our daily lives, for example a class representing a rectangle with properties of height, width and area, could mark the area property as derived (/area) since its value can be calculated by the simple formula (area = height x width). There are examples where the derivation is not practical or doesn't hold true, and in these cases an annotation or description on the class is useful to avoid confusion or wrong assumptions.