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diff --git a/methods.mtask.tex b/methods.mtask.tex
index 837933d..db31782 100644
--- a/methods.mtask.tex
+++ b/methods.mtask.tex
@@ -1,15 +1,14 @@
-\section{mTask}
 The \gls{mTask}-\gls{EDSL} is the basis on which the system is built. The
-\gls{mTask} was created by Koopman et al.\ to support several views such as an
-\gls{iTasks} simulation and a \gls{C}-code generator. The \gls{EDSL} was
-designed to generate a ready to compile \gls{TOP}-like system for
+\gls{mTask}-\gls{EDSL} was created by Koopman et al.\ to support several views
+such as an \gls{iTasks} simulation and a \gls{C}-code generator. The \gls{EDSL}
+was designed to generate a ready to compile \gls{TOP}-like system for
 microcontrollers such as the Arduino\cite{koopman_type-safe_nodate}%
 \cite{plasmeijer_shallow_2016}.
 
 The \gls{mTask}-\gls{EDSL} is a shallowly embedded class based \gls{EDSL} and
 therefore it is very suitable to have a new backend that partly implements the
-given classes. The following subsections show the details of the \gls{EDSL}
-that are used in the extension. The parts of the \gls{EDSL} that are not used
+given classes. The following sections show the details of the \gls{EDSL}
+that are used in this extension. The parts of the \gls{EDSL} that are not used
 will not be discussed and the details of those parts can be found in the cited
 literature.
 
@@ -36,15 +35,56 @@ instance isExpr Upd
 instance isExpr Expr
 \end{lstlisting}
 
-\subsection{Expressions}
+\section{Semantics}
+The \gls{C}-backend of the \gls{mTask}-system has an engine that is generated
+alongside the code for the \glspl{Task}. This engine will execute the
+\glspl{mTask} according to certain rules and semantics.
+\glspl{mTask} do not behave like functions but more like
+\gls{iTasks}-\glspl{Task}. An \gls{mTask} is queued when either his timer runs
+out or when it is started by another \gls{mTask}. When an \gls{mTask} is
+queued it does not block the execution but it will return immediately while
+the actual \gls{Task} will be executed some time in the future.
+
+The \gls{iTasks}-backend simulates the \gls{C}-backend and thus uses the same
+semantics. This engine expressed in pseudocode is listed as
+Algorithm~\ref{lst:engine}. All the \glspl{Task} are inspected on their waiting
+time. When the waiting time has not passed the delta is subtracted and they are
+pushed to the end of the queue. When the waiting has has surpassed they are
+executed. When a \gls{mTask} wants to queue another \gls{mTask} it can just
+append it to the queue.
+
+\begin{algorithm}[H]
+	\KwData{\textbf{queue} queue$[]$, \textbf{time} $t, t_p$}
+
+	$t\leftarrow\text{now}()$\;
+	\Begin{
+		\While{true}{
+			$t_p\leftarrow t$\;
+			$t\leftarrow\text{now}()$\;
+			\If{notEmpty$($queue$)$}{
+				$task\leftarrow \text{queue.pop}()$\;
+				$task$.wait $-= t-t_p$\;
+				\eIf{$task.wait>t_0$}{
+					queue.append$(task)$\;
+				}{
+					run\_task$(task)$\;
+				}
+			}
+		}
+	}
+	\caption{Engine pseudocode for the \gls{C}- and
+		\gls{iTasks}-backends}\label{lst:engine}
+\end{algorithm}
+
+\section{Expressions}
 Expressions in the \gls{mTask}-\gls{EDSL} are divided into two types, namely
 boolean expressions and arithmetic expressions. The class of arithmetic
 language constructs also contains the function \CI{lit} that lifts a
 host-language value in to the \gls{EDSL} domain. All standard arithmetic
-functions are included but are omitted for brevity. Moreover the class
-restrictions are only shown in the first functions and are later omitted. Both
-the boolean expression and arithmetic expression classes are shown in
-Listing~\ref{lst:arithbool}.
+functions are included in the \gls{EDSL} but are omitted in the example for
+brevity. Moreover, the class restrictions are only shown in the first functions
+and omitted in subsequent funcitons. Both the boolean expression and arithmetic
+expression classes are shown in Listing~\ref{lst:arithbool}.
 
 \begin{lstlisting}[language=Clean,label={lst:arithbool},
 	caption={Basic classes for expressions}]
@@ -60,10 +100,27 @@ class boolExpr v where
   (==.) infix 4 :: (v a p) (v a q) -> v Bool Expr       | ==, toCode a & ...
 \end{lstlisting}
 
-\subsection{Control flow}
-\todo{Write this}
+\section{Control flow}
+Looping of \glspl{Task} happens because \glspl{Task} are launched at regular
+intervals or relaunch themselves. Therefore there is no need for loop control
+flow functionality such as \emph{while} or \emph{for} constructions. The main
+control flow is the sequence operator and the \emph{if} statement. Both are
+shown in Listing~\ref{lst:control}. The first class of \emph{If} statements
+describe the regular \emph{if} statement. The expressions given can have any
+role. The functional dependency on \CI{s} determines the return type of the
+statement.  The sequence operator is very straightforward and just ties the two
+expressions together in sequence.
 
-\subsection{Input/Output and class extensions}
+\begin{lstlisting}[%
+	language=Clean,label={lst:control},caption={Control flow operators}]
+class If v q r ~s where
+  If :: (v Bool p) (v t q) (v t r) -> v t s | ...
+
+class seq v where
+  (:.) infixr 0 :: (v t p) (v u q) -> v u Stmt | ...
+\end{lstlisting}
+
+\section{Input/Output and class extensions}
 All expressions that have an \CI{Upd} role can be assigned to. Examples of such
 expressions are \glspl{SDS} and \gls{GPIO}. Moreover, class extensions can be
 created for specific peripherals such as user LEDs. The classes facilitating
@@ -95,7 +152,7 @@ class assign v where
 \end{lstlisting}
 
 A way of storing data in \glspl{mTask} is using \glspl{SDS}. \glspl{SDS} serve
-as variables in the \gls{mTask} and will keep their value across executions.
+as variables in the \gls{mTask} and maintain their value across executions.
 The classes associated with \glspl{SDS} are listed in
 Listing~\ref{lst:sdsclass}. The \CI{Main} class is introduced to box an
 \gls{mTask} and make it recognizable by the type system.
@@ -109,13 +166,13 @@ class sds v where
   sds :: ((v t Upd)->In t (Main (v c s))) -> (Main (v c s)) | ...
 \end{lstlisting}
 
-\subsection{Example \gls{mTask}}
+\section{Example mTask}
 \todo{Also explain semantics about running tasks}
-Some example \glspl{mTask} using almost all of the functionality are show in
+Some example \glspl{mTask} using almost all of the functionality are shown in
 Listing~\ref{lst:exmtask}. The \glspl{mTask} shown in the example do not belong
 to a particular view and therefore are of the type \CI{View t r}. The
 \CI{blink} \gls{mTask} show the classic \emph{Arduino} \emph{Hello World!}
-application that blinks a certain LED every interval. The \CI{thermostat}
+application that blinks a certain LED at each interval. The \CI{thermostat}
 \gls{mTask} will enable a digital pin powering a cooling fan when the analog
 pin representing a temperature sensor is too high. \CI{thermostat`} shows the
 same program but now using the assignment style \gls{GPIO}.