Does column dba_hist_active_sess_history.delta_read_io_bytes counts only data or includes index read

Hello,

We are trying to have a sense of how much data is being read by our internal users and we are considering using dba_hist_active_sess_history.delta_read_io_bytes.

That column is defined like this:

"Number of I/O bytes read by this session over the last DELTA_TIME microseconds"

However, it's not clear what is included in the number of I/O bytes read.

Thanks

Nico