# Refcount behavior is given for all PyObject* types: 0 (no change), +1
# (increment) and -1 (decrement). A blank refcount field indicates the
# parameter or function value is not a PyObject* and is therefore not
-# subject to reference counting.
+# subject to reference counting. A special case for the value "null"
+# (without quotes) is used for functions which return a PyObject* type but
+# always return NULL. This is used by some of the PyErr_*() functions, in
# The parameter names are as they appear in the API manual, not the source