user story
US000 As a ordinary user, I want to login the system.

US001 As an Engineer,I want to submit/revoke IT Request,and view all reqest submitted by myself.
US002 As a SDM, I want to view all the IT Request submitted by the Engineers who report to me, and I can approve or reject these Requests as well.
US003 As an IT Manager, I want to view all IT Request.
US004 As an IT Staff, I want to view all new IT Request and be able to modify the status.
US005 As an Administrator, I want to view all users information, and be able to create/delete/update users.
US006 As an IT Manager, I want to operate the request types.
US007 As an SDM, I can submit IT Requests which are unvisialbe to Engineers.
US008 As a ordinary user, I want be able to change my login password.