There is no operation that connects this variable to the independent variables.
yes_connected
There is one or more operations that connects this variable to the independent variables.
sum_connected
There is only one parrent that connects this variable to the independent variables and the parent is a summation operation; i.e., AddvvOp, AddpvOp, SubpvOp, SubvpOp, or SubvvOp.
csum_connected
Satisfies the sum_connected assumptions above and in addition this variable is the result of summation operator.
cexp_connected
This node is only connected in the case where the comparision is true for the conditional expression with index connect_index.