diff --git a/src/multi_install/abc/menu_service_abc.py b/src/multi_install/abc/menu_service_abc.py
index cdf5593..3f7db2a 100644
--- a/src/multi_install/abc/menu_service_abc.py
+++ b/src/multi_install/abc/menu_service_abc.py
@@ -10,10 +10,7 @@ class MenuServiceABC(ABC):
     def run(self): pass
     
     @abstractmethod
-    def select_os(self) -> str: pass
+    def select_os(self) -> bool: pass
     
     @abstractmethod
-    def main_menu(self) -> str: pass
-    
-    @abstractmethod
-    def select_collection(self) -> str: pass
+    def main_menu(self) -> bool: pass
diff --git a/src/multi_install/model/main_menu_enum.py b/src/multi_install/model/main_menu_enum.py
new file mode 100644
index 0000000..4aaee8b
--- /dev/null
+++ b/src/multi_install/model/main_menu_enum.py
@@ -0,0 +1,17 @@
+from enum import Enum
+
+
+class MainMenuEnum(Enum):
+
+    install_collection = 'Install collection'
+    uninstall_collection = 'Uninstall collection'
+    add_collection = 'Add collection'
+    remove_collection = 'Remove collection'
+    
+    install_application = 'Install application'
+    uninstall_application = 'Uninstall application'
+    add_application = 'Add application'
+    remove_application = 'Remove application'
+    
+    back = 'Back'
+    exit = 'Exit'