The 166 page "March 2013 Watchlisting Guidance" was jointly authored by 19 agencies, and has been released in full on The Intercept.
As Jeremy Scahill and Ryan Devereaux point out in their analysis, the document is positively Kafkaesque, allowing agencies to add you to the watchlist if you are suspected of associating with a person who is suspected of being under suspicion of being a terrorist -- and "terrorist" has been redefined to include "people who damage government property," and people who seek to "influence government policy through intimidation."
This document -- and the millions who've been placed under suspicion as a result of it -- owes its existence to the Obama administration and its face-saving drive to expand the list of surveillance targets in the wake of the unsuccessful "underwear bomber" plot.
The criteria allow people to be put under suspicion without "concrete facts" and establishes thresholds as low as a single uncorroborated tweet or Facebook post. It also provides for adding whole "classes" of people to the list without any particular individual suspicion.
One interesting aspect of this document and the accompanying reportage: the accompanying article does not identify Edward Snowden as its source, and is deliberately vague about its provenance. This may be further evidence of a second NSA leaker -- a big deal, since Edward Snowden was the first person to ever leak NSA documents to the press. However, given the number of agencies involved in the document's creation, it may be that the leak came from another agency.
The Secret Government Rulebook For Labeling You a Terrorist [Jeremy Scahill and Ryan Devereaux/The Intercept]