UniServerInstance is a global function defined in uniGUIServer.pas which returns the global instance of the ServerModule singleton.
uniGUIServer.pas
Declaration (in unit uniGUIServer):
uniGUIServer
unit uniGUIServer; interface function UniServerInstance: TUniGUIServerModule; ...
Related page: ServerModule — https://unigui.com/doc/online_help/server_module.htm