diff --git a/command.py b/command.py
index 96d7848..4398852 100644
--- a/command.py
+++ b/command.py
@@ -136,7 +136,7 @@
 
     groups = mp.config.GetString('manifest.groups')
     if not groups:
-      groups = 'all,-notdefault,platform-' + platform.system().lower()
+      groups = 'default,platform-' + platform.system().lower()
     groups = [x for x in re.split(r'[,\s]+', groups) if x]
 
     if not args:
diff --git a/project.py b/project.py
index 22e4a5d..901a283 100644
--- a/project.py
+++ b/project.py
@@ -672,9 +672,14 @@
        project_groups: "all,group1,group2"
        manifest_groups: "-group1,group2"
        the project will be matched.
+
+       The special manifest group "default" will match any project that
+       does not have the special project group "notdefault"
     """
-    expanded_manifest_groups = manifest_groups or ['all', '-notdefault']
+    expanded_manifest_groups = manifest_groups or ['default']
     expanded_project_groups = ['all'] + (self.groups or [])
+    if not 'notdefault' in expanded_project_groups:
+      expanded_project_groups += ['default']
 
     matched = False
     for group in expanded_manifest_groups:
diff --git a/repo b/repo
index 6b374f7..c348474 100755
--- a/repo
+++ b/repo
@@ -164,7 +164,8 @@
                  help='create a shallow clone with given depth; see git clone')
 group.add_option('-g', '--groups',
                  dest='groups', default='default',
-                 help='restrict manifest projects to ones with a specified group',
+                 help='restrict manifest projects to ones with specified '
+                      'group(s) [default|all|G1,G2,G3|G4,-G5,-G6]',
                  metavar='GROUP')
 group.add_option('-p', '--platform',
                  dest='platform', default="auto",
diff --git a/subcmds/init.py b/subcmds/init.py
index 1131260..29730cc 100644
--- a/subcmds/init.py
+++ b/subcmds/init.py
@@ -91,8 +91,9 @@
                  dest='depth',
                  help='create a shallow clone with given depth; see git clone')
     g.add_option('-g', '--groups',
-                 dest='groups', default='all,-notdefault',
-                 help='restrict manifest projects to ones with a specified group',
+                 dest='groups', default='default',
+                 help='restrict manifest projects to ones with specified '
+                      'group(s) [default|all|G1,G2,G3|G4,-G5,-G6]',
                  metavar='GROUP')
     g.add_option('-p', '--platform',
                  dest='platform', default='auto',
@@ -169,7 +170,7 @@
 
     groups = [x for x in groups if x]
     groupstr = ','.join(groups)
-    if opt.platform == 'auto' and groupstr == 'all,-notdefault,platform-' + platform.system().lower():
+    if opt.platform == 'auto' and groupstr == 'default,platform-' + platform.system().lower():
       groupstr = None
     m.config.SetString('manifest.groups', groupstr)