diff --git a/app/scodoc/sco_bulletins.py b/app/scodoc/sco_bulletins.py
index 6cfdb25b..3fd15859 100644
--- a/app/scodoc/sco_bulletins.py
+++ b/app/scodoc/sco_bulletins.py
@@ -28,6 +28,7 @@
 """Génération des bulletins de notes
 
 """
+import collections
 import email
 import time
 import numpy as np
@@ -143,7 +144,7 @@ def formsemestre_bulletinetud_dict(formsemestre_id, etudid, version="long"):
     nt: NotesTableCompat = res_sem.load_formsemestre_results(formsemestre)
     if not nt.get_etud_etat(etudid):
         raise ScoValueError("Étudiant non inscrit à ce semestre")
-    I = scu.DictDefault(defaultvalue="")
+    I = collections.defaultdict(str)
     I["etudid"] = etudid
     I["formsemestre_id"] = formsemestre_id
     I["sem"] = formsemestre.get_infos_dict()
@@ -260,7 +261,7 @@ def formsemestre_bulletinetud_dict(formsemestre_id, etudid, version="long"):
         # n'affiche pas le rang sur le bulletin s'il y a des
         # notes en attente dans ce semestre
         rang = scu.RANG_ATTENTE_STR
-        rang_gr = scu.DictDefault(defaultvalue=scu.RANG_ATTENTE_STR)
+        rang_gr = collections.defaultdict(lambda: scu.RANG_ATTENTE_STR)
     inscriptions_counts = nt.get_inscriptions_counts()
     I["rang"] = rang
     I["rang_gr"] = rang_gr
@@ -710,50 +711,15 @@ def etud_descr_situation_semestre(
     decisions_ue        : noms (acronymes) des UE validées, séparées par des virgules.
     descr_decisions_ue  : ' UE acquises: UE1, UE2', ou vide si pas de dec. ou si pas show_uevalid
     descr_mention : 'Mention Bien', ou vide si pas de mention ou si pas show_mention
+    descr_parcours : le nom (libelle) du parcours dans lequel est inscrit l'étudiant en BUT (vide ailleurs)
     """
     # Fonction utilisée par tous les bulletins (APC ou classiques)
-    cnx = ndb.GetDBConnexion()
-    infos = scu.DictDefault(defaultvalue="")
+    infos = collections.defaultdict(str)
 
     # --- Situation et décisions jury
-    # démission/inscription ?
-    events = sco_etud.scolar_events_list(
-        cnx, args={"etudid": etudid, "formsemestre_id": formsemestre_id}
-    )
-    date_inscr = None
-    date_dem = None
-    date_def = None
-    for event in events:
-        event_type = event["event_type"]
-        if event_type == "INSCRIPTION":
-            if date_inscr:
-                # plusieurs inscriptions ???
-                # date_inscr += ', ' +   event['event_date'] + ' (!)'
-                # il y a eu une erreur qui a laissé un event 'inscription'
-                # on l'efface:
-                log(
-                    f"etud_descr_situation_semestre: removing duplicate INSCRIPTION event for etudid={etudid} !"
-                )
-                sco_etud.scolar_events_delete(cnx, event["event_id"])
-            else:
-                date_inscr = event["event_date"]
-        elif event_type == "DEMISSION":
-            # assert date_dem == None, 'plusieurs démissions !'
-            if date_dem:  # cela ne peut pas arriver sauf bug (signale a Evry 2013?)
-                log(
-                    f"etud_descr_situation_semestre: removing duplicate DEMISSION event for etudid={etudid} !"
-                )
-                sco_etud.scolar_events_delete(cnx, event["event_id"])
-            else:
-                date_dem = event["event_date"]
-        elif event_type == "DEFAILLANCE":
-            if date_def:
-                log(
-                    f"etud_descr_situation_semestre: removing duplicate DEFAILLANCE event for etudid={etudid} !"
-                )
-                sco_etud.scolar_events_delete(cnx, event["event_id"])
-            else:
-                date_def = event["event_date"]
+
+    date_inscr, date_dem, date_def = _dates_insc_dem_def(etudid, formsemestre_id)
+
     if show_date_inscr:
         if not date_inscr:
             infos["date_inscription"] = ""
@@ -851,6 +817,49 @@ def etud_descr_situation_semestre(
     return infos, dpv
 
 
+def _dates_insc_dem_def(etudid, formsemestre_id) -> tuple:
+    "Cherche les dates d'inscription, démission et défaillance de l'étudiant"
+    cnx = ndb.GetDBConnexion()
+    events = sco_etud.scolar_events_list(
+        cnx, args={"etudid": etudid, "formsemestre_id": formsemestre_id}
+    )
+    date_inscr = None
+    date_dem = None
+    date_def = None
+    for event in events:
+        event_type = event["event_type"]
+        if event_type == "INSCRIPTION":
+            if date_inscr:
+                # plusieurs inscriptions ???
+                # date_inscr += ', ' +   event['event_date'] + ' (!)'
+                # il y a eu une erreur qui a laissé un event 'inscription'
+                # on l'efface:
+                log(
+                    f"etud_descr_situation_semestre: removing duplicate INSCRIPTION event for etudid={etudid} !"
+                )
+                sco_etud.scolar_events_delete(cnx, event["event_id"])
+            else:
+                date_inscr = event["event_date"]
+        elif event_type == "DEMISSION":
+            # assert date_dem == None, 'plusieurs démissions !'
+            if date_dem:  # cela ne peut pas arriver sauf bug (signale a Evry 2013?)
+                log(
+                    f"etud_descr_situation_semestre: removing duplicate DEMISSION event for etudid={etudid} !"
+                )
+                sco_etud.scolar_events_delete(cnx, event["event_id"])
+            else:
+                date_dem = event["event_date"]
+        elif event_type == "DEFAILLANCE":
+            if date_def:
+                log(
+                    f"etud_descr_situation_semestre: removing duplicate DEFAILLANCE event for etudid={etudid} !"
+                )
+                sco_etud.scolar_events_delete(cnx, event["event_id"])
+            else:
+                date_def = event["event_date"]
+    return date_inscr, date_dem, date_def
+
+
 def _format_situation_fields(
     infos, field_names: list[str], extra_values: list[str]
 ) -> None:
diff --git a/app/scodoc/sco_evaluations.py b/app/scodoc/sco_evaluations.py
index 799a0e03..9bfcfd4c 100644
--- a/app/scodoc/sco_evaluations.py
+++ b/app/scodoc/sco_evaluations.py
@@ -27,6 +27,7 @@
 
 """Evaluations
 """
+import collections
 import datetime
 import operator
 import time
@@ -171,8 +172,8 @@ def do_evaluation_etat(evaluation_id, partition_id=None, select_first_partition=
 
     # On considere une note "manquante" lorsqu'elle n'existe pas
     # ou qu'elle est en attente (ATT)
-    GrNbMissing = scu.DictDefault()  # group_id : nb notes manquantes
-    GrNotes = scu.DictDefault(defaultvalue=[])  # group_id: liste notes valides
+    GrNbMissing = collections.defaultdict(int)  # group_id : nb notes manquantes
+    GrNotes = collections.defaultdict(list)  # group_id: liste notes valides
     TotalNbMissing = 0
     TotalNbAtt = 0
     groups = {}  # group_id : group
diff --git a/app/scodoc/sco_formsemestre_inscriptions.py b/app/scodoc/sco_formsemestre_inscriptions.py
index cdbe2c57..1e993a35 100644
--- a/app/scodoc/sco_formsemestre_inscriptions.py
+++ b/app/scodoc/sco_formsemestre_inscriptions.py
@@ -27,6 +27,7 @@
 
 """Opérations d'inscriptions aux semestres et modules
 """
+import collections
 import time
 
 import flask
@@ -543,10 +544,8 @@ def formsemestre_inscription_option(etudid, formsemestre_id):
     mods = sco_moduleimpl.moduleimpl_withmodule_list(formsemestre_id=formsemestre_id)
     inscr = sco_moduleimpl.do_moduleimpl_inscription_list(etudid=etudid)
     # Formulaire
-    modimpls_by_ue_ids = scu.DictDefault(defaultvalue=[])  # ue_id : [ moduleimpl_id ]
-    modimpls_by_ue_names = scu.DictDefault(
-        defaultvalue=[]
-    )  # ue_id : [ moduleimpl_name ]
+    modimpls_by_ue_ids = collections.defaultdict(list)  # ue_id : [ moduleimpl_id ]
+    modimpls_by_ue_names = collections.defaultdict(list)  # ue_id : [ moduleimpl_name ]
     ues = []
     ue_ids = set()
     initvalues = {}
diff --git a/app/scodoc/sco_modalites.py b/app/scodoc/sco_modalites.py
index b12e54e7..1f79201a 100644
--- a/app/scodoc/sco_modalites.py
+++ b/app/scodoc/sco_modalites.py
@@ -33,8 +33,8 @@ Elle n'est pas utilisée pour les parcours, ni pour rien d'autre
 (c'est donc un attribut "cosmétique").
 
 """
+import collections
 import app.scodoc.notesdb as ndb
-import app.scodoc.sco_utils as scu
 from app import log
 
 
@@ -54,7 +54,7 @@ def group_sems_by_modalite(sems):
     """Given the list of fromsemestre, group them by modalite,
     sorted in each one by semestre id and date
     """
-    sems_by_mod = scu.DictDefault(defaultvalue=[])
+    sems_by_mod = collections.defaultdict(list)
     modalites = list_formsemestres_modalites(sems)
     for modalite in modalites:
         for sem in sems:
diff --git a/app/scodoc/sco_moduleimpl_inscriptions.py b/app/scodoc/sco_moduleimpl_inscriptions.py
index 7de236be..06c7ffb1 100644
--- a/app/scodoc/sco_moduleimpl_inscriptions.py
+++ b/app/scodoc/sco_moduleimpl_inscriptions.py
@@ -27,6 +27,7 @@
 
 """Opérations d'inscriptions aux modules (interface pour gérer options ou parcours)
 """
+import collections
 from operator import itemgetter
 
 import flask
@@ -676,7 +677,7 @@ def get_etuds_with_capitalized_ue(formsemestre_id: int) -> list[dict]:
     """For each UE, computes list of students capitalizing the UE.
     returns { ue_id : [ { infos } ] }
     """
-    ues_cap_info = scu.DictDefault(defaultvalue=[])
+    ues_cap_info = collections.defaultdict(list)
     formsemestre = FormSemestre.query.get_or_404(formsemestre_id)
     nt: NotesTableCompat = res_sem.load_formsemestre_results(formsemestre)
 
diff --git a/app/scodoc/sco_prepajury.py b/app/scodoc/sco_prepajury.py
index 24619dcc..9ec0a95b 100644
--- a/app/scodoc/sco_prepajury.py
+++ b/app/scodoc/sco_prepajury.py
@@ -27,6 +27,7 @@
 
 """Feuille excel pour préparation des jurys classiques (non BUT)
 """
+import collections
 import time
 
 from openpyxl.styles.numbers import FORMAT_NUMBER_00
@@ -64,10 +65,10 @@ def feuille_preparation_jury(formsemestre_id):
         "partition_id"
     ]
 
-    prev_moy_ue = scu.DictDefault(defaultvalue={})  # ue_code_s : { etudid : moy ue }
+    prev_moy_ue = collections.defaultdict(dict)  # ue_code_s : { etudid : moy ue }
     prev_ue_acro = {}  # ue_code_s : acronyme (à afficher)
     prev_moy = {}  # moyennes gen sem prec
-    moy_ue = scu.DictDefault(defaultvalue={})  # ue_acro : moyennes { etudid : moy ue }
+    moy_ue = collections.defaultdict(dict)  # ue_acro : moyennes { etudid : moy ue }
     ue_acro = {}  # ue_code_s : acronyme (à afficher)
     moy = {}  # moyennes gen
     moy_inter = {}  # moyenne gen. sur les 2 derniers semestres
diff --git a/app/scodoc/sco_pv_forms.py b/app/scodoc/sco_pv_forms.py
index 46cf7d61..af6cb65b 100644
--- a/app/scodoc/sco_pv_forms.py
+++ b/app/scodoc/sco_pv_forms.py
@@ -29,7 +29,7 @@
 
 Formulaires paramétrage PV et génération des tables
 """
-
+import collections
 import time
 from reportlab.platypus import Paragraph
 from reportlab.lib import styles
@@ -283,7 +283,7 @@ def formsemestre_pvjury(formsemestre_id, format="html", publish=True):
     H.append(tab.html())
 
     # Count number of cases for each decision
-    counts = scu.DictDefault()
+    counts = collections.defaultdict(int)
     for row in rows:
         counts[row["decision"]] += 1
         # add codes for previous (for explanation, without count)
diff --git a/app/scodoc/sco_report.py b/app/scodoc/sco_report.py
index 3d8bb3c7..4cb0d7ca 100644
--- a/app/scodoc/sco_report.py
+++ b/app/scodoc/sco_report.py
@@ -29,6 +29,7 @@
   - statistiques decisions
   - suivi cohortes
 """
+import collections
 import os
 import tempfile
 import re
@@ -178,7 +179,8 @@ def _results_by_category(
         if etud[category] in Count:
             Count[etud[category]][etud[result]] += 1
         else:
-            Count[etud[category]] = scu.DictDefault(kv_dict={etud[result]: 1})
+            Count[etud[category]] = collections.defaultdict(int, {etud[result]: 1})
+
     # conversion en liste de dict
     C = [Count[cat] for cat in categories]
     # Totaux par lignes et colonnes
@@ -551,7 +553,7 @@ def table_suivi_cohorte(
     indices_sems.sort()
     for p in P:
         p.nb_etuds = 0  # nombre total d'etudiants dans la periode
-        p.sems_by_id = scu.DictDefault(defaultvalue=[])
+        p.sems_by_id = collections.defaultdict(list)
         for s in p.sems:
             p.sems_by_id[s["semestre_id"]].append(s)
             p.nb_etuds += len(s["members"])
@@ -1162,7 +1164,7 @@ def table_suivi_cursus(formsemestre_id, only_primo=False, grouped_parcours=True)
         civilites,
         statuts,
     ) = tsp_etud_list(formsemestre_id, only_primo=only_primo)
-    codes_etuds = scu.DictDefault(defaultvalue=[])
+    codes_etuds = collections.defaultdict(list)
     for etud in etuds:
         etud["code_cursus"], etud["decisions_jury"] = get_code_cursus_etud(etud)
         codes_etuds[etud["code_cursus"]].append(etud)
@@ -1350,17 +1352,16 @@ def graph_cursus(
             civilites,
             statuts,
         )
-    edges = scu.DictDefault(
-        defaultvalue=set()
-    )  # {("SEM"formsemestre_id_origin, "SEM"formsemestre_id_dest) : etud_set}
+    edges = collections.defaultdict(set)
+    # {("SEM"formsemestre_id_origin, "SEM"formsemestre_id_dest) : etud_set}
 
     def sem_node_name(sem, prefix="SEM"):
         "pydot node name for this integer id"
         return prefix + str(sem["formsemestre_id"])
 
     sems = {}
-    effectifs = scu.DictDefault(defaultvalue=set())  # formsemestre_id : etud_set
-    decisions = scu.DictDefault(defaultvalue={})  # formsemestre_id : { code : nb_etud }
+    effectifs = collections.defaultdict(set)  # formsemestre_id : etud_set
+    decisions = collections.defaultdict(dict)  # formsemestre_id : { code : nb_etud }
     isolated_nodes = []  # [ node_name_de_formsemestre_id, ... ]
     connected_nodes = set()  # { node_name_de_formsemestre_id }
     diploma_nodes = []
diff --git a/app/scodoc/sco_utils.py b/app/scodoc/sco_utils.py
index d56466c3..03d3ecc9 100644
--- a/app/scodoc/sco_utils.py
+++ b/app/scodoc/sco_utils.py
@@ -30,7 +30,7 @@
 """
 import base64
 import bisect
-import copy
+import collections
 import datetime
 from enum import IntEnum
 import io
@@ -270,32 +270,11 @@ def get_mention(moy):
         return ""
 
 
-class DictDefault(dict):  # obsolete, use collections.defaultdict
-    """A dictionnary with default value for all keys
-    Each time a non existent key is requested, it is added to the dict.
-    (used in python 2.4, can't use new __missing__ method)
-    """
-
-    defaultvalue = 0
-
-    def __init__(self, defaultvalue=0, kv_dict={}):
-        dict.__init__(self)
-        self.defaultvalue = defaultvalue
-        self.update(kv_dict)
-
-    def __getitem__(self, k):
-        if k in self:
-            return self.get(k)
-        value = copy.copy(self.defaultvalue)
-        self[k] = value
-        return value
-
-
-def group_by_key(d, key):
-    gr = DictDefault(defaultvalue=[])
+def group_by_key(d: dict, key) -> dict:
+    grouped = collections.defaultdict(lambda: [])
     for e in d:
-        gr[e[key]].append(e)
-    return gr
+        grouped[e[key]].append(e)
+    return grouped
 
 
 # ----- Global lock for critical sections (except notes_tables caches)