The file   cate90.train_stemed_svm_.train  is the vectors for the reuters21578 training data.
The file  cate90.test_stemed_svm_.test  is the vectors for the reuters21578 test data.

The format of these two files is very similar to the svmlight format. Every row is a vector.
each row has the format like:
id1:value1 id2:value2 id3:value3 .....

cate90.train.rel.read_d and cate90.test.rel.read_d file show the relevence judgement of reuters21578 traing and testing data.