Meta data of text file
I can think of lots of metadata that even a plain text file has -- creator, size, permissions, last accessed time, last modified time, etc. -- some of which probably depend on which OS you're talking about. I'd suggest looking at the directory operations and/or the file data structures in the system libraries on the particular OS for a more complete list for each particular OS.
Depending on the usage of the file, it might contain some metadata -- for example, a script file might indicate the program used to run the script at the top -- but in general a plain text file doesn't contain metadata itself.