Under the CIP a SSN is an identification number. The Exam states "An identification number for a U.S. person is a taxpayer identification number (TIN) (or evidence of an application for one), and an identification number for a non-U.S. person is one or more of the following: a TIN; a passport number and country of issuance; an alien identification card number; or a number and country of issuance of any other unexpired government-issued document evidencing nationality or residence and bearing a photograph or similar safeguard. TIN is defined by section 6109 of the Internal Revenue Code of 1986 (26 USC 6109) and the IRS regulations implementing that section (e.g., Social Security number (SSN), individual taxpayer identification number (ITIN), or employer identification number)."
An ITIN is an acceptable identification number.
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"100 victories in 100 battles isnt the most skillful. Subduing the other's military w/o battle is the most skillful." Sun-Tzu