afni.nimh.nih.gov

Technically, you should use 3dbucket, not 3dTcat. As Rick pointed out, 3dTcat adds a "time axis". This is a relatively unimportant point, but since your consolidated dataset's 4th dimension isn't time (or any continuous parameter), pretending that it is time doesn't feel right.

Historically, 3dbucket came first and 3dTcat is a minor adaptation of that code. Someday I should write down a history of AFNI development, as far as I can remember it.

bob cox