Fallback value

A parameter, which is demanded by a target page, can be populated by the caller with a value. It is also possible to string fallback values together in this case. Based on the principle of "first match", the first fallback value to deliver a valid value will be used at run-time. Parameter values, which are the same for all or at least the majority of callers, can already be predefined with values at the target page. A fallback value chain can also be created here. If the caller does not provide a valid value for the parameter, then the fallback value chain of the target page will be worked through and the first valid value found will be used. If a valid value for a required parameter cannot be identified neither from the caller nor at the target page, then the target page cannot be viewed/used.