From the routine ^XUP:
DUZ(DA) ;Build DUZ for a user. Used by Mailman.
;(p284) Make the setting of several DUZ parts conditional.
N Y
S Y(0)=$G(^VA(200,+DA,0)),Y("XUS")=$G(^XTV(8989.3,1,"XUS"))
S DUZ=DA
S:$G(DUZ(0))'="@" DUZ(0)=$P(Y(0),"^",4)
S DUZ(1)="",DUZ("AG")=$P($G(^XTV(8989.3,1,0)),"^",8)
S:'$G(DUZ(2)) DUZ(2)=$O(^VA(200,DUZ,2,0))
S:'DUZ(2) DUZ(2)=+$P(Y("XUS"),"^",17)
S:'$L($G(DUZ("LANG"))) DUZ("LANG")=$P(Y("XUS"),"^",7)
Q
as you can see DUZ(2) comes from ^VA(200,DUZ,2,<entry>,0) or from $P(^XTV(8989.3,1,"XUS"),"^",17)
From FileMan List File Attributes option:
^VA(200,D0,2,0)=^200.02P^^ (#16) DIVISION
^VA(200,D0,2,D1,0)= (#.01) DIVISION [1P:4] ^ (#1) DEFAULT [2S] ^
^XTV(8989.3,D0,XUS)= ^ (#202) DEFAULT # OF ATTEMPTS [2N] ^ (#203) DEFAULT
==>LOCK-OUT TIME [3N] ^ (#204) DEFAULT MULTIPLE SIGN-ON
==>[4S] ^ (#205) ASK DEVICE TYPE AT SIGN-ON [5S] ^ (#206)
==>DEFAULT AUTO-MENU [6S] ^ (#207) DEFAULT LANGUAGE
==>[7P:.85] ^ ^ (#209) DEFAULT TYPE-AHEAD [9S] ^ (#210)
==>DEFAULT TIMED-READ (SECONDS) [10N] ^ (#211) BYPASS
==>DEVICE LOCK-OUT [11S] ^ (#212) RESERVED [12S] ^ (#213)
==>RESERVED [13S] ^ (#212.5) FAILED ACCESS ATTEMPT AUDIT
==>[14S] ^ (#214) LIFETIME OF VERIFY CODE [15N] ^ (#216)
==>INTERACTIVE USER'S PRIORITY [16N] ^ (#217) DEFAULT
==>INSTITUTION [17P:4] ^ (#218) DEFAULT AUTO SIGN-ON [18S]
==>^ (#219) DEFAULT MULTIPLE SIGN-ON LIMIT [19N] ^
So the "2" nodes in the NEW PERSON File #200 specify which institution a person is working within, and if they are not defined, it defaults to DEFAULT INSTITUTION (Field #217 ) of the KERNEL SYSTEM PARAMETERS File #8989.3
As to using FileMan to add patients, there are business rules implicit in the VistA code which may or may not be enforced by the Data Dictionary. You might mess yourself up by ignoring the proper way to put data into the system. I can't be exact in saying whether you will or will not hurt your data acquisition because I don't know which data you are putting in using FileMan, and I don't know how complete you are being in maintaining the complete data entry.
Best Regards,
David