Adding metadata / identifier data to a CSV file?

Question

Is there a way to add a \"tag\" (add a unique metadata/identifier) to a CSV file without affecting the contents or ability to read/write the file?

I am using Python, but

Answer 1

In case you are not sure that all possible readers/writers of the file will be able to interpret (and preserve) comments, create the tag in a second file using some name convention that links them. Example:

myCSVFile.csv
myCSVFile.csv.tag

Answer 2

Just add comment lines that you can parse later.

#Creator:JohnSmith
#Date:....
#Columns:id,username,...
1,JohnSmith
2, ..

Answer 3

This would be compliant with W3C embedded metadata format: http://www.w3.org/TR/tabular-data-model/#embedded-metadata

#publisher,W3C
#updated,2015-10-17T00:00:00Z
#name,sensor,temperature
#datatype,string,float
sensor,temperature
s-1,25.5