The Master app function of NStack can be used in the situation of white labelling applications.
It allows the creation of one master app and several children apps that inherit sections / keys/ apps from the master app. A good example would be the creation of a "template" / generic festival app; the children apps can be considered partical festivals (e.g. one app for the Roskilde Festival, one app for the Uhørt festival, one app for Tommorowland, etc.).
As stated above, the children apps will inherit sections / keys / apps from the "template" festival app (e.g. error messages, login screens), but certain sections / keys / apps can be modified to be unique to the specific festival (splash screen title, etc.).
The Master app function is accesable from NStack app's main screen.
From the new screen that is dispalyed on screen, in the upper-right corner the option for Sync - Master app appears.