[Mne_analysis] Evoked setno = 0 in MNE python

[Kambiz Tavabi]

Hello list,
I am a bit confused about a couple instances of defining setno = 0 while 
loading evoked data in the context of (1) computing an inverse operator 
& (2) computing inverse solution on evoked data, using MNE-python. The 
exact line is as follows; evoked = Evoked(fname_evoked, setno=0, 
baseline=(None, 0)). What does this mean? Does setno = 0 in above (1) 
default to an inverse operator for each condition in the evoked data 
set; and similarly does setno=0 result in an stc file for all conditions 
in (2). If I am wrong, then should I be looping through condition numbers?

And, in python for dummies lingo, how does one compute the mean 
activation time series in a label?

FYI the argument setno=0 is used in tutorials found @:
http://martinos.org/mne/auto_examples/inverse/plot_make_inverse_operator.html
http://martinos.org/mne/auto_examples/inverse/plot_compute_mne_inverse.html

Thanks in advance
Kam