Say 'only during initialization' instead of 'at the initial time only'

Since the equations aren't active during the initial event iteration, it sounds a bit misleading (although not logically incorrect) to say that they are used at the initial time only.

chapters/introduction.tex

@@ -65,7 +65,7 @@ \section{Scope of the Specification}\label{scope-of-the-specification}
 \end{itemize}
 
 Therefore, a flat hybrid DAE is seen as a set of equations where some of the equations are only conditionally evaluated.
-Initial setup of the model is specified using start-values and equations that hold at the initial time only.
+Initial setup of the model is specified using start-values and equations that hold only during initialization.
 
 A Modelica class may also contain annotations, i.e.\ formal comments,
 which specify graphical representations of the class (icon and diagram),