I am applying for OSS user logins. I just want to know will there be different roles for each technology in SAP. If yes then, i will provide my technology details also in that (ie., xi)
That really depends on your compnay. There could be many administraotr usually basis team will have that right , they usually responsible for opening your system for SAP to login.
Are you looking for sending user id and password for SAP to login to your system , if yes pls check note 508140. If you are looking for creating S ids for users in your compnay you can do it in service.sap.com --> Keys and Request. I dont think users can see passwords each other. Once you create a user SAP will send you the S id and password and the user needs to change after the first log in.And only administrators can maintain the user details, functionalities are restricted through security
To search OSS notes u have to get into http://service.sap.com/notes but u need to have OSS user ID and password to access OSS NOTES.
SAP provides support in the form of Notes also and this is called OSS. Can check the link Sree provided.
Just for an example if you face any error in your system. Then there is error number associated with the error. Then you can search for the OSS not for the error number, and the note will give you possible solution to your problem