some more clarifications suggested by William Newman

doc/section_emitters.tex

@@ -17,7 +17,7 @@ types is shown below:
 Generally, light sources are specified as children of the \code{<scene>} element; for instance,
 the following snippet instantiates a point light emitter that illuminates a sphere.
 \begin{xml}
-<scene version="0.4.0">
+<scene version=$\MtsVer$>
 	<emitter type="point">
 		<spectrum name="intensity" value="1"/>
 		<point name="position" x="0" y="0" z="-2"/>
@@ -28,7 +28,7 @@ the following snippet instantiates a point light emitter that illuminates a sphe
 An exception to this are \emph{area lights}, which turn a geometric object into a light source.
 These are specified as children of the corresponding \code{<shape>} element.
 \begin{xml}
-<scene version="0.4.0">
+<scene version=$\MtsVer$>
 	<shape type="sphere">
 		<emitter type="area">
 			<spectrum name="radiance" value="1"/>

doc/section_integrators.tex

@@ -134,3 +134,36 @@ enable the alpha channel in the scene's film instance (Section~\ref{sec:films}).
       \caption{\label{fig:hideemitters}An example application of the \code{hideEmitters} parameter
     together with alpha blending}
 }
+\subsubsection*{Number of samples per pixel}
+Many of the integrators in Mitsuba depend on a number of \emph{samples per pixel}, which is related
+to the amount of noise in the final output. However, it is important to note that this parameter is
+\emph{not} a parameter of the integrator.
+Instead, it must be declared in the \code{<sampler>} instantiation, which is nested inside the
+\code{<sampler>} element. The rationale behind this is that the sensor is responsible for performing
+a measurement using a specified sampling strategy. The integrator declares the high-level strategy
+for resolving scattering interactions, but does not depend on a specific number of samples.
+
+\begin{xml}
+<scene version=$\MtsVer$>
+    <!-- ... scene contents ... -->
+
+    <integrator type=".. integrator type ..">
+        <!-- ... integrator parameters ... -->
+    </integrator>
+
+    <sensor type="... sensor type ...">
+        <!-- ... sensor parameters ... -->
+
+        <sampler type=" ... sampler type ... ">
+            <!-- ... sampler parameters ... -->
+
+            <!-- Important: number of samples per pixel goes here -->
+            <integer name="sampleCount" value="32"/>
+        </sampler>
+
+        <film type=" ... film type ... ">
+            <!-- ... film parameters ... -->
+        </film>
+    </sensor>
+</scene>
+\end{xml}

doc/section_sensors.tex

@@ -4,8 +4,32 @@
 In Mitsuba, \emph{sensors}, along with a \emph{film}, are responsible for recording radiance
 measurements in some usable format. This includes default choices such as perspective
 or orthographic cameras, as well as more specialized sensors that measure the radiance
-into a given direction or the irradiance received by a certain surface. The following
+into a given direction or the irradiance received by a certain surface. This subsection
-section lists the available choices.
+lists the available choices.
+
+\subsubsection*{Syntax}
+In the XML scene description language, a sensor declaration looks as follows
+\begin{xml}
+<scene version=$\MtsVer$>
+    <!-- ... scene contents ... -->
+
+    <sensor type="... sensor type ...">
+        <!-- ... sensor parameters ... -->
+
+        <sampler type=" ... sampler type ... ">
+            <!-- ... sampler parameters ... -->
+        </sampler>
+
+        <film type=" ... film type ... ">
+            <!-- ... film parameters ... -->
+        </film>
+    </sensor>
+</scene>
+\end{xml}
+In other words, the \code{<sensor>} declaration is a child element of the \code{<scene>} (the particular
+position in the scene file does not play a role). Nested within the sensor declaration is a
+sampler instance (described in Section~\ref{sec:samplers}) and a film instance (described in
+Section~\ref{sec:films}).
 
 \subsubsection*{Handedness convention}
 Sensors in Mitsuba are \emph{right-handed}.