The MCvDTreeSplit type exposes the following members.
When it equals to 1, the inverse split rule is used (i.e. left and right branches are exchanged in the expressions below)
Pointer to the next split in the node split list
The split quality, a positive number. It is used to choose the best primary split, then to choose and sort the surrogate splits. After the tree is constructed, it is also used to compute variable importance
Index of the variable used in the split