Clarified parameter expression.

Also explain one special case of parameter expression.

chapters/synchronous.tex

@@ -239,7 +239,7 @@ \subsection{Argument Restrictions (Component Expression)}\label{argument-restric
 is not possible for a general expression.
 
 The reason for restricting an input argument to be an evaluable expression is that the value of the input argument needs to be evaluated during translation, in order that clock analysis can be performed during translation.
-In some cases there is a special handling of parameter expressions, which indicates that their values are not needed during translation.
+In some cases the text specifies a special handling of parameter expressions, in that case their values are not needed during translation.
 \end{nonnormative}
 
 \begin{example}
@@ -382,6 +382,7 @@ \section{Clock Constructors}\label{clock-constructors}
 Therefore, for sorting the input argument is treated as known.
 The given interval and time shift can be modified by using the \lstinline!subSample!, \lstinline!superSample!, \lstinline!shiftSample! and \lstinline!backSample! operators on the returned clock, see \cref{sub-clock-conversion-operators}.
 There are restrictions where this operator can be used, see \lstinline!Clock! expressions below.
+Note that $\mathit{interval}$ does not have to an evaluable expression, since different real interval clocks are never compared.
 \end{nonnormative}
 \end{semantics}
 \end{operatordefinition*}