Fix additional issue in #2182

chapters/synchronous.tex

@@ -1383,6 +1383,8 @@ \subsection{Inferencing of solverMethod}\doublelabel{inferencing-of-solvermethod
 For each sub-clock partition we build a set corresponding to this sub-clock partition.
 These sets are then merged as follows: for each set without a specified solverMethod we merge it 
 with sets connected to it (these may contain a solverMethod); and this is repeated until it is not possible to merge more sets.
+The sets connected in this way should be part of the same base-clock partition and connected through a sub-clock conversion operator  
+(\lstinline!subSample!, \lstinline!superSample!, \lstinline!shiftSample! or \lstinline!backSample!).
 
 \begin{itemize}
 \item If this set contains multiple different values for \lstinline!solverMethod! it is an error.