Index: trunk/doc/user/06_features/simulation/index.html
===================================================================
--- trunk/doc/user/06_features/simulation/index.html	(revision 8840)
+++ trunk/doc/user/06_features/simulation/index.html	(revision 8841)
@@ -182,11 +182,43 @@
 expect to work (std_cschem for things like the connect attribute, std_devmap
 for the devmap and portmap mechanisms).
 
-<H3 autotoc="yes"> Low level simulation </H3>
+<H3 autotoc="yes"> Low level (raw) simulation </H3>
 <p>
-TODO
+The low level, raw, simulation mechanism is used to enable an sch-rnd project
+to export to circuit simulation, e.g. spice. The high level simulation is
+built on top of the low level.
+<p>
+The low level simulation consists of:
+<ul>
+	<li> a set of <a href="../../07_io/export_spice/index.html">conventional attributes</a>
+	     and mechanisms built on top of them
+	<li> a set of <a href="../../07_io/target_spice/index.html">the target_spice</a>
+	     plugin which tunes the compilation so that the abstract model is
+	     usable for spice netlist export
+	<li> a view, normally called spice_raw, which uses target_spice as the target
+	     engine
+</ul>
+<p>
+The normal workflow is:
+<ul>
+	<li> set the view to spice_raw
+	<li> fill in all relevant attributes in symbols
+	<li> add extra symbols (e.g. voltage sources)
+	<li> compile and export using the spice export format
+	<li> maybe edit the exported file (e.g. gnucap requires that because of incompatibility)
+	<li> run a spice simulator on the exported file
+</ul>
+<p>
+The extra symbols drawn for spice simulation may interfere with other workflows,
+e.g. if the same project is used as a soruce for a PCB workflow. There are
+multiple mechanisms to deal with this:
+<ul>
+	<li> the classic approach: draw spice-related extras on separate sheet and do not include that sheet in workflows different than spice
+	<li> use <a href="#test_benching">test benching</a> or project stances in general to omit them
+	<li> the PCB workflow will automatically omit any component from the export that does not have a footprint attribute
+</ul>
 
-<H3 autotoc="yes"> Test benching </H3>
+<H3 autotoc="yes" id="test_benching"> Test benching </H3>
 <p>
 The test bench mechanism is responsible for selecting parts of the circuit
 for simulation. Test benching operatos on project level. It is implemented