Summary : User SID can be use as arguments for /ui /ue /mu options
If you are using /ui:DOMAIN\User or /ue:DOMAIN\User options to include
or exclude specific user, you need to have a connection to the domain.
Otherwise, the specified usernames are unused. The LookupAccountSid API
call will try to map the specified user name with its SID.
When no domain connection is avalaible (i.e in offline mode), you can use /ue:<User SID> or /ui:<User SID>
The User SID can be use with /mu options.
Examples :
/mu:<User SID>:NEWDOMAIN\UserName
See more on this :
Scanstate /UI /UE rules with user names are ignored
http://blogs.technet.com/b/askds/archive/2010/02/18/usmt-4-and-winpe-common-issues.aspx
and
USMT 4: Migration offline for selected profile
http://myitforum.com/cs2/blogs/mathieucl/archive/2010/01/25/usmt-4-migration-offline-for-selected-profile.aspx