diff --git a/development/scons/slack-desc b/development/scons/slack-desc
index 9b1c24e784..f4e8f68e2d 100644
--- a/development/scons/slack-desc
+++ b/development/scons/slack-desc
@@ -1,4 +1,12 @@
-scons: SCons
+# HOW TO EDIT THIS FILE:
+# The "handy ruler" below makes it easier to edit a package description.  Line
+# up the first '|' above the ':' following the base package name, and the '|'
+# on the right side marks the last column you can put a character in.  You must
+# make exactly 11 lines for the formatting to be correct.  It's also
+# customary to leave one space after the ':'.
+
+     |-----handy-ruler------------------------------------------------------|
+scons: SCons (Open Source software construction tool)
 scons:
 scons: SCons is an Open Source software construction tool--that is,
 scons: a next-generation build tool.  Think of SCons as an improved,