To overwrite the system alias that you defined in transaction LPD_CUST or the launchpad designer for the target application, you use the sap-system parameter for Web Dynpro applications, SAP GUI for HTML transactions, and SAPUI5 Fiori apps.
This topic is relevant only for application developers.
The sap-system parameter has to be passed as part of the intent, for example, #SalesOrder-display?sap-system=<system alias>.
After overwriting the system alias, the navigation is directed to the target system with the given system alias. For example, if end users search for a purchase order in the SAP Fiori launchpad, you are directed to the target system such as an ERP or SRM system at runtime based on the search result.
The application changes the system for the target application dynamically at runtime based on the value of the sap-system parameter.
The target application can be a Web Dynpro application, an SAP GUI for HTML transaction, or an SAPUI5 application.
If you provide a system alias from the sap-system parameter that cannot be resolved, there is a fallback to the front-end server system.