Add comment with warning about possible accidental misuse of 'compone…

…nt expression'

chapters/operatorsandexpressions.tex

@@ -1290,7 +1290,11 @@ \subsection{Event-Related Operators with Function Syntax}\label{event-related-op
 pre($y$)
 \end{lstlisting}\end{synopsis}
 \begin{semantics}
-Returns the \emph{left limit} $y(t^{-})$ of variable $y(t)$ at a time instant $t$.  At an event instant, $y(t^{-})$ is the value of $y$ after the last event iteration at time instant $t$ (see comment below). Any subscripts in the component expression $y$ must be parameter expressions.  \lstinline!pre! can be applied if the following three conditions are fulfilled simultaneously: (a) variable $y$ is either a subtype of a simple type or is a record component, (b) $y$ is a discrete-time expression (c) the operator is \emph{not} applied in a \lstinline!function! class.
+Returns the \emph{left limit} $y(t^{-})$ of variable $y(t)$ at a time instant $t$.
+At an event instant, $y(t^{-})$ is the value of $y$ after the last event iteration at time instant $t$ (see comment below).
+% Warning "component expression" is a term defined for synchronous operator argument restrictions; this seems to conflict with also defining the present argument restriction below.
+Any subscripts in the component expression $y$ must be parameter expressions.
+\lstinline!pre! can be applied if the following three conditions are fulfilled simultaneously: (a) variable $y$ is either a subtype of a simple type or is a record component, (b) $y$ is a discrete-time expression (c) the operator is \emph{not} applied in a \lstinline!function! class.
 \begin{nonnormative}
 This can be applied to continuous-time variables in when-clauses, see \cref{discrete-time-expressions} for the definition of discrete-time expression.
 \end{nonnormative}