--- a/AbstractSourceCodeManager.st	Fri Feb 10 11:17:21 2017 +0100
+++ b/AbstractSourceCodeManager.st	Fri Feb 10 11:22:33 2017 +0100
@@ -1782,6 +1782,14 @@
     ^ '1.0'
 !
 
+isAbstract
+    "Return if this class is an abstract class.
+     True is returned here for myself only; false for subclasses.
+     Abstract subclasses must redefine this again."
+
+    ^ self == AbstractSourceCodeManager.
+!
+
 isContainerBased
     "true, if the SCM uses some kind of source container (,v files).
      False, if it is like a database or filesystem."