Github user alpinegizmo commented on a diff in the pull request:
https://github.com/apache/flink/pull/4992#discussion_r150194036
--- Diff: docs/dev/stream/operators/windows.md ---
@@ -978,6 +978,24 @@ input
</div>
</div>
+### Using per-window state in ProcessWindowFunction
+
+In addition to accessing keyed state (as any rich function can) a
`ProcessWindowFunction` can
+also use keyed state that is scoped to the window that the function is
currently processing. The are
--- End diff --
The are --> There are
---
