diff -r 36268865b9bf -r 007e0e70ef13 src/pyams_skin/interfaces/extension.py
--- a/src/pyams_skin/interfaces/extension.py	Fri Nov 10 13:48:12 2017 +0100
+++ b/src/pyams_skin/interfaces/extension.py	Wed Nov 15 17:02:31 2017 +0100
@@ -36,6 +36,28 @@
 ACTIVATION_MODES = SimpleVocabulary([SimpleTerm(k, title=v) for k, v in ACTIVATION_MODES_LABELS.items()])
 
 
+GOOGLE_TAGS_INFO_KEY = 'pyams_skin.tagmanager_info'
+
+
+class IGoogleTagManagerInfo(Interface):
+    """Google Tag Manager account info"""
+
+    enabled = Bool(title=_("Activate Google Tag Manager?"),
+                   description=_("Is Google Tag Manager activated?"),
+                   required=True,
+                   default=False)
+
+    container_id = TextLine(title=_("Container ID"),
+                            description=_("Google Tag Manager container ID (may start with 'GTM-')"),
+                            required=False)
+
+    activation_mode = Choice(title=_("Activation mode"),
+                             description=_("Mode(s) in which Google Tags are activated"),
+                             vocabulary=ACTIVATION_MODES,
+                             default=ACTIVATED_ON_BOTH,
+                             required=True)
+
+
 GOOGLE_ANALYTICS_INFO_KEY = 'pyams_skin.analytics_info'