This is a Special Purpose Artist.
Used for writer/composer (and related) credits when the work in question pre-dates any written or recorded version(s), having originally been passed down from musician to musician. Rather than being attributable to one anonymous or unknown artist/collaboration, this work is better described as having emerged from a musical tradition.
Please note that the IPI code 00039657154 is also used by right societies for works that have passed into the public domain even if the writer/composer is known. Use the known artist when attributing a work instead.