What's in the /process_data/taskContext/object/assignedUser/@initials ?
is it meant for the middle initial of user's name? or what?
how do I use AdminUI to populate that field?
The initials field is one of the values that can be set in your LDAP.
It can represent the middle name of the user.
You won't be able to use the adminui to populate that field.
You would have to create the user in LDAP and set the initials and then sync it.