It may serve as a specific identifier or version number (v17) for a private dataset being indexed by a "crawler" (a bot that systematically browses the web).
Navigation and Entry: The 17th protocol emphasizes non-destructive entry. Night crawlers are not vandals. They use specialized footwear with high-friction rubber soles for scaling vertical surfaces and traversing narrow ledges without leaving marks or making noise. The Ethics of the Shadow fu10 night crawling 17
If "FU10" refers to a specific game version or group designation, it may relate to the tabletop RPG Nightcrawlers It may serve as a specific identifier or