diff --git a/sw_model/sw_model.tex b/sw_model/sw_model.tex
index 042613f..674b512 100644
--- a/sw_model/sw_model.tex
+++ b/sw_model/sw_model.tex
@@ -1,6 +1,24 @@
-% $Id: ons calling functionsin Exp $
 
-% 
+%
+% strucure
+%
+% introduce concept, mapping s/w to FMMD
+%
+% yourdon data flow. Show transform bubbles and process for converting to a hierarchy of functiona calls
+% show h/w at the bottom, and s/w on top.
+% describe where s/w h/w interface occurs
+%
+% Talk about pre and post coonditions of contract s/w
+% get some nice refs on contract s/w
+% Now make the distinction that
+% pre condition violations are like componnt fault modes, and that a software function is
+% like a {\fg}. Now show that an analysed s/w function is a {\dc} where the 
+% symptoms of failure are failed post conditions.
+
+% now take a simple example, temp sensing
+% and design it top down.
+% interface to digitial I/O and an ADC
+
 
 \ifthenelse {\boolean{paper}}
 {