I find nothing interesting.
So you glanced at all the Oracle blog links in that Google search, as well as all those other online discussions that also appeared from the Google search, and nothing helps?
I guess you'll have to hope someone else chooses to respond because I've never used the tool, nor do I anticipate needing to use it in the near future. Thus I cannot be of further assistance.
You need to look at the fileinfo_t structure here:
"The fi_name field contains the name of the file but does not include any directory components. If no file information is associated with an I/O, the fi_name field will be set to the string <none>. In some rare cases, the pathname associated with a file might be unknown. In this case, the fi_name field will be set to the string <unknown>."