diff --git a/Running-from-source.md b/Running-from-source.md
index b3e5d04..2881c49 100644
--- a/Running-from-source.md
+++ b/Running-from-source.md
@@ -9,10 +9,14 @@
 * `develop` is targeted at Python 3.9 and has no guarantee about working on 
   earlier Python versions.
 
+In general you can check the contents of the file `.python-version` in the 
+source for the version that code is targeting.  This file is *not* included 
+in the Windows installers/packages as it's not necessary.
+
 ## Ensure Python is installed
 
-On Windows or macOS Download and install an appropriate version from
-[python.org](https://python.org).
+On Windows or macOS Download and install an appropriate version of CPython
+('Core Python') from [python.org](https://python.org).
 
 **You need a 32-bit version on Windows as this application has some code 
 that calls OS APIs that needs changing for 64-bit and we've not yet had the