diff --git a/didacto/controller.py b/didacto/controller.py
index 0dca1f1d8670bceb578105d930e5f77f891af525..76b3c0d98fc758e045404d14a905fe82472feb58 100644
--- a/didacto/controller.py
+++ b/didacto/controller.py
@@ -183,7 +183,7 @@ class Controller:
             for key in metadata_in:
                 metadata_out[key]=metadata_in[key]
             if '/AAPL:Keywords' in metadata_out: 
-                metadata_out.pop('/AAPL:Keywords') # to fix some bug with sibelius6 - MacOs pdf
+                metadata_out.pop('/AAPL:Keywords') # this fixes some bug with sibelius6 - MacOs pdf
             print(metadata_out)
             print(type(metadata_out))
 
diff --git a/didacto/model.py b/didacto/model.py
index c6df3943bbca7b9f5044d61ec6646382b4d4a9cc..d7a05ba9d6a1d832ce4556af5862af2b6932a1a3 100644
--- a/didacto/model.py
+++ b/didacto/model.py
@@ -153,6 +153,17 @@ class Model:
         
 
 class UserData():
+    '''This Class stores user data, keyword definition and categories
+    curent {'keyword1':'definition1', etc.}
+    future {'keyword1':{'definition':'definition1',
+                        'categories':['cat1','cat2', etc.]
+                        }}
+    simpler {'keyword1':'definition1',['cat1','cat2','cat3']}
+
+    even simpler, two different dics, in two files
+    or go for sql lite ???
+    '''
+
     def __init__(self, data, ):
         self.user_data=data
 
@@ -162,6 +173,18 @@ class UserData():
     def set(self,key,data):
         self.user_data[key] = data
 
+
+# new methods to handle keywords categories
+    def get_categories(self,key):
+        return self.user_data[key][1]
+
+    def set_categries(self,key,cat):
+        self.user_data[key][1] = cat
+
+
+
+
+
     def retrieve(self):
         return self.user_data