[M4IF Technotes] elementary stream location in mp4 file

[Ariel David]

Hi,
I am trying to decode mp4 files that have simple profile video in them.
In other words, I am trying to extract simple profile video from mp4 files.
I've gone through the system standard and managed to read and decode the different atoms.
I can't seem to find anywhere an atom that tells me the elementary stream location in the MDAT atom.
At first I thought it would be in the DREF (url or urn) atom, but I could not find it there.
Which atom holds this information if at all?  
Can someone point me to mp4 files with simple profile video in them?  I have the 4 different "lastword" mp4 files and that's it.
Thanks,
Ariel