It is not always a good idea to put your index bands in the same file as the original bands, because they will probably have different data ranges. The index bands will likely have much smaller data values. So, they will not have a comparable influence on the classification as the original bands. You could avoid this problem by rescaling all of your data in some way. But you will have to decide what is a reasonable way to rescale them, to get the results you want. But to put aside the question of whether it's a good idea to but your index images and original bands together, you can do it using the tool found under File > Save File As > ENVI Standard. In the resulting dialog, you can choose the Import button to import first you original bands, then your index images into the same output image. - Peg