[jdp23]

This is similar to Mar Ambinder's explanation in "Solving the PRISM myseter" [1] and Robert O'Harrow et al's quotes from intelligence sources in "U.S., company officials: Internet surveillance does not indiscriminately mine data" [2]. From the second article, discussing "direct access":

Intelligence community sources said that this description, although inaccurate from a technical perspective, matches the experience of analysts at the NSA. From their workstations anywhere in the world, government employees cleared for PRISM access may “task” the system and receive results from an Internet company without further interaction with the company’s staff.

According to a more precise description contained in a classified NSA inspector general’s report, also obtained by The Post, PRISM allows “collection managers [to send] content tasking instructions directly to equipment installed at company-controlled locations,” rather than directly to company servers. The companies cannot see the queries that are sent from the NSA to the systems installed on their premises, according to sources familiar with the PRISM process.

Crucial aspects about the mechanisms of data transfer remain publicly unknown. Several industry officials told The Post that the system pushes requested data from company servers to classified computers at FBI facilities at Quantico. The information is then shared with the NSA or other authorized intelligence agencies.