diff --git a/fmmd_concept/fmmd_concept.tex b/fmmd_concept/fmmd_concept.tex
index 4d59bc4..67f116c 100644
--- a/fmmd_concept/fmmd_concept.tex
+++ b/fmmd_concept/fmmd_concept.tex
@@ -180,7 +180,8 @@ failure mode behaviour for say, differnet ambient pressures or temperatures.
 If $E$ is the number of applied states or environmental conditions to consider
 in a system, the job of the bottom-up analyst is complicated by a cross product factor again 
 $(N-1) \times N \times K \times E$.
-If we put some typical very small embedded system numbers into this, say $N=100$, $K=2.5$ and $E=10$
+If we put some typical very small embedded system numbersi\footnote{these figures would
+be typical of a very simple temperature controller, with a micro-controller sensor and heater circuit} into this, say $N=100$, $K=2.5$ and $E=10$
 we have $99 \times 100 \times 2.5 \times 10 = 247500 $.
 To look in detail at a quarter of a million test cases is obviously impractical.