diff --git a/swh/model/model.py b/swh/model/model.py
--- a/swh/model/model.py
+++ b/swh/model/model.py
@@ -511,6 +511,7 @@
     DSC = "dsc"
     SUBVERSION = "svn"
     MERCURIAL = "hg"
+    CVS = "cvs"
 
 
 def tuplify_extra_headers(value: Iterable):