diff --git a/pep-0511.txt b/pep-0511.txt
index 44faf4080..4a0766139 100644
--- a/pep-0511.txt
+++ b/pep-0511.txt
@@ -277,6 +277,19 @@ Prototype::
 Parameters:
 
 * *code*: code object
+* *context*: an object with an *optimize* attribute (``int``), the optimization
+  level (0, 1 or 2). The value of the *optimize* attribute comes from the
+  *optimize* parameter of the ``compile()`` function, it is equal to
+  ``sys.flags.optimize`` by default.
+
+Each implementation of Python can add extra attributes to *context*. For
+example, on CPython, *context* will also have the following attribute:
+
+* *interactive* (``bool``): true if in interactive mode
+
+XXX add more flags?
+
+XXX replace flags int with a sub-namespace, or with specific attributes?
 
 The method must return a code object.