I mean adding meta data, not the observations itself. E.g. information about when where data collected, how was it done, or if I use simple name of the file like CorporatePerformance.sav, just information which of my billion files was it (CorporatePerformanceAfterCleaning5BeforeRecoding8withPaulsChanges.sav).
Perfect! Thank you, Bruce. Works with my SPSS 24 as well. Also, while trying to find option Add document in a menu (I am a simple person, I prefer clicking to writing syntax), I found that the same way works Utilities - Data File Comments.