The difference should be in the other order.

The equalityConstraint should be smaller than the size of the variable.

chapters/classes.tex

@@ -1084,7 +1084,7 @@ \section{Balanced Models}\label{balanced-models}
   I.e., top-level inputs are treated as known variables.  This represents the number of binding equations that will be provided when the class is used.
   \end{nonnormative}
 \item
-  For over-determined connectors, \cref{equation-operators-for-overconstrained-connection-based-equation-systems1}, each spanning tree without any root node adds the difference between the size of the output of \lstinline!equalityConstraint! and the size of the over-determined type or record.
+  For over-determined connectors, \cref{equation-operators-for-overconstrained-connection-based-equation-systems1}, each spanning tree without any root node adds the difference between the size of the over-determined type or record and the size of the output of \lstinline!equalityConstraint!.
 \begin{nonnormative}
   By definition this term is zero in simulation models, but relevant for checking component models.
   There are no other changes in the variable and equation count for models -- but a restriction on the size of the output of \lstinline!equalityConstraint!, \cref{balancing-restriction-and-size-of-connectors}.