--- a/doc/makefile-variables.txt	Fri Jun 13 10:00:52 2014 -0600
+++ b/doc/makefile-variables.txt	Fri Jun 13 12:36:52 2014 -0700
@@ -98,6 +98,17 @@
   studio_OPT.$(MACH).$(BITS) versions of this available if greater specificity
   is needed.
 
+* TPNO is the Third Party number (i.e., a numeric value): the License
+  Technology from the Product Lifecycle Suite tool.  This should be used
+  in the common case when there is just one TPNO for a component.  We
+  recommend that this be near the top of any Makefile, just below the
+  various COMPONENT_foo definitions.
+* TPNO_foo is for the rare case (~3% of components) when a component has
+  more than one TPNO.  Each one should have a separate short but descriptive
+  name substituted for "foo".  This likewise should be near the top of any
+  Makefile, just below the various COMPONENT_foo definitions, and it must
+  also be before the inclusion of ips.mk .
+
 ---
 
 Now switching from explaining the function of specific variables to a more