Prepare Windows installer for 2.2a1.
diff --git a/PCbuild/BUILDno.txt b/PCbuild/BUILDno.txt
index 8791f52f..3285567 100644
--- a/PCbuild/BUILDno.txt
+++ b/PCbuild/BUILDno.txt
@@ -33,6 +33,8 @@
 
 Windows Python BUILD numbers
 ----------------------------
+  21    2.2a1       TENTATIVE
+        18-Jul-2001
   20    2.1.1       TENTATIVE
         20-Jul-2001
   19    2.1.1c1