Startup Test

 is Disc 1, Track 5 on the Xenosaga Original Soundtrack and Disc 2, Track 4 on the album. ('Startup Test' is an unofficial translation, as seen in the VGMdb listing of the album.)

It is split into two parts. The first part plays in the following cutscenes:
 * The M-type enemies are replaced with G-type enemies in KOS-MOS's Encephalon.
 * The Drone GX appears in KOS-MOS's Encephalon.
 * Virgil and his crew unwittingly prepare to fire upon Shion in the Woglinde.
 * Mary telepathically transmits the data from the U-TIC Battleship's motherframe to Shelly.
 * Lapis Roman briefs the party on what they need to do in order to prove the Kukai foundation's innocence.
 * Miyuki and Shion discuss how to stop the Song of Nephilim.
 * The party prepares to depart for Proto Merkabah in the Elsa.

The second part (from 1:27) plays when KOS-MOS activates the Hilbert Effect in her Encephalon.