This package is based on the code in rpart.  The extensions implemented here
relate to new methods for growing trees and are achieved primary by
additions/modifications to rpart's C code for recursive partitioning.  
Users access this function mostly via the arguments to the itree() function.  

rpart implements many ideas besides just tree-growing, including snipping,
pruning, plotting etc. For the most part itree inherits these with little to
no adjustments by virtue of being an extension of rpart.  The help files indicate
where the functionality is new, adjusted, or the same as compared to rpart.  The
source code is similarly documented.

As itree copies most of rpart's code the authors of rpart are authors 
of this package as well.  However, please direct any error reports 
or other questions about itree maintainer of this package (not rpart's); 
they are welcome and appreciated.