The term dependency is used to identify different values for the same parameter (or any other block for that matter).
Parameter values often have dependencies, such as dependency on atomic element (Iron, Methane, Oxygen), on media (concrete/clay/rock) or on location (Paris, Gothenburg, Kampala).
The number of dependencies for a parameter determines its dimension. A parameter with one dependency is referred to as a vector parameter, two dependencies gives a matrix parameter.
A type of dependency is defined using an index-list, which is a named list of indices.