( See the bottom of the message for the 'Suggestion' part . )
Not all the experiments arise from the scratch every time )
-- sometimes (and very often) one may have a serious need to do a set of routine changes in his or her previous experiments;
for example, one may look at shafi's post in
http://community.cedrus.com/showthread.php?t=45 , 
at bgon's post at
http://community.cedrus.com/showthread.php?t=57 , 
and at WSHorton's post at
http://community.cedrus.com/showthread.php?t=199 . 
Last but not least ),
I can also report that we have tens of old experiments,
having tens of 'events' stimuli in each, tens of "trials" and tens of blocks also .
( Making a brief note, I should say that using stimulus lists is not an option due to some technical reasons like lack of control )
I was told that making a set of simple uniform changes in all of them via the straightforward "click-and-edit" way took like one month of human time ,
though this amount can be slightly overestimated .
As it can be easily seen from  --  and
http://community.cedrus.com/archive/...php/t-130.html  ,
Superlab users seem to have expected to be able to do such a “mass change” operation on experiment files .
Cedrus seem to admit that this feature is one of the most demanded
( , Hisham's answer ) , promising to implement sort of a solution in the upcoming intermediate SuperLab 4.5 release, but there is obviously not enough time to implement that yet:
Hisham's answer in , and the FAQ link
http://www.cedrus.com/support/superlab/tn1501_faq.htm  ,
stating that the 4.5 version release date is estimated to be the Fall of 2007 .
At the moment I am writing this,
there is no evidence of version 4.5 in the list of the new updates
( http://community.cedrus.com/forumdisplay.php?f=13 ),
the 4.0.5 version release info also does not have any notifications about the new features from the "top demand" list
( http://community.cedrus.com/showthread.php?t=316 )
So the only solution to deal with “old” SuperLab 4.* files that is available at the moment is the Greg Shenaut’s ‘sl4util’  (manages only stimulus lists): officially unsupported by Cedrus ( see the Hisham's reply ) but sort of recommended to use (see  ) .
Before writing sl4util, Greg has also proposed to open the .sl4 data format (as an option, see  ), but at that moment this proposal was not accepted.
From the other hand, it looks like Greg's attempts to hack the SuperLab data format were encouraged by the Cedrus team (  ) .
Is obviously to open the .sl4 experiment file format: from the one hand, I personally can not imagine how the one can be used to run an experiment without the SuperLab software; from the other hand, we see (see the above links) that Cedrus obviously lacks the time to develop a solution for the "mass editing" problem, while the users (who can concentrate on their own needs) can sometimes do that surprisingly quickly (see Greg's report where he says it took like one weekend for him to make some significant progress even having no experiment file format description).
I do not call Cedrus to make any "stated in the stone" statements -- let it be something "unsupported" and "subject to change" -- basically, I personally just don't want to waste time hacking a thing that can be simply (and harmlessly) documented .
Actually, if there is a significant lack of time ( so it is hard to devote it to the .sl4 file format description), I might even suggest to open the code of the .sl4 file saving procedure (well, in the case if there are no solutions one will want to keep undisclosed).
Anyway, thanks for reading this,
PS. I'd like to say that the program itself is very nice designed, and, what impressed me even more -- the support on the forum looks to have an immediate reaction .
This looks to be very positively accepted by the users, so I wish to Cedrus to go in a more intensive collaboration with them .