404. That’s an error.

The requested URL /bookmarks/mark?op=add&title=Station+P671+%28NCalifornia+Network%29&annotation=&nui=1&service=bookmarks&bkmk=http%3A%2F%2Fearthquake.usgs.gov%2Fmonitoring%2Fgps%2FNCalifornia%2Fp671%2F was not found on this server. That’s all we know.