No, the .ctb file contains images of each slice, a couple of model images (a file icon and an image to be displayed while printing), and a list of gCode commands telling the printer how to print the model. The gCode is derived from various profile settings, however it is not, nor does it need to be, the entire profile.

To preserve custom profiles you need to them export from the Print Settings dialog--(singly or "all"):

Here are the contents of the .ctb file for a small 1 mm thick custom washer (a .ctb file is an encrypted and compressed "archive" of this information) :
file list:

file images:

run.gcode partial contents:

Cliff Knight No, the .ctb file contains images of each slice, a couple of model images to be displayed while prin ...

Hello

Wow! That’s an expert answer, THANK YOU very much !
So if I don’t remember which resin parameter I have used for a previous print, there is no way to know it, even with the ctb file. Oops that is not very handy…

In the future remember to backup ("export") your customized print profiles, into a location that will survive re-installation of Chitubox--AND backup, Backup, BACKUP--EVERYTHING!!! 

Someday your whole system will crash and you will lose it all without proper backups; it's not a question of IF, but rather WHEN?

In case anyone cares, here's  the "START" and "LAYER 0"  gCode from the "run.gcode" file with comments:

Cliff Knight In the future remember to backup ("export") your customized print profiles, into a locatio ...

Yes you are totally right!
I made a back up of my profile.
But but my problem of knowing the parameters used by an old file is still there. For my next print I'll do it the old-fashioned way, I'll write it down with pen and paper ;)