These simulation data are described on the revised page 384-5 of the
book. See the errata file for a revised version if your book is not
the fourth or later printing.

There are 50 x four datasets - training and test data for the four
dimensional problem, and training and test data for the 10
dimensional problem.

These come in four files. 
For example, orange4.train is a 5000 x 5 matrix consisting of 
fifty datasets of size 100 x 5. The first column is the -1/1 output,
the remaining four are the inputs.

orange4.test is 50000 x 5, since for each training set of size 100,
there is a test set of size 1000. Hence it has 50 test sets.