The term “identifiers” is NSA jargon for information relating to an individual, such as telephone number, email address, IP address and username as well as their name.
The document – which is undated, though metadata suggests this version was last updated in June 2012 – does not say whether the oversight process it mentions has been established or whether any searches against US person names have taken place.
James Ball and Spencer Ackerman, “NSA loophole allows warrantless search for US citizens’ emails and phone calls”
Perhaps foolishly, but I find it amusing that metadata is being used to evaluate how/when other metadata identifiers were being used to track the world’s populations…