More than once I have been asked, co-workers, or people in a forum if you can put comments on an SPFILE. In the old times it was very usual to comment when changing a parameter (with the date of the change and the old value in case there were performance problems) or when you put some new parameter. Seeing these changes was easy, since the init.ora is at the end a text file. The problem we can have with SPFILE since this is a bianrio file, ofcourse to you can make a strings to SPFILE and see some things. The correct thing is to dump SPFILE to a text file.
So, to put a comment in SPFILE the same alter sentence allows us with the comment clause, look at the example below;
alter system set “optimizer_adaptive_features”=true comment =’21.06.2017 Changed by Antonio NAVARRO’ scope=both sid=’*’;
HTH – Antonio NAVARRO