The relationship is defined at the model and mapping layer.
Note:
At the highest level, an OBIEE Metadata Repository includes three layers of information:
1.
First, a Physical layer is defined. The metadata layer identifies the source data.
2.Second, a Business Model and Mapping layer is defined. This metadata layer organizes the physical layer into logical categories and records the appropriate metadata for access to the source data.
3.Finally, the Presentation layer is defined. This metadata layer exposes the business model entities for end- user access.

Object-level security controls the visibility to business logical objects based on a user's role. You can set up object-level security for metadata repository objects, such as subject areas and presentation folders, and for Web objects, such as dashboards and dashboard pages, which are defined in the Presentation Catalog.
1) Business logic object
This controls access to objects, such as:
*subject areas
*presentation tables
*presentation columns
For example, users in a particular department can view only the subject areas that belong to their department.
2) Web object security
This provides security for objects stored in the Web Catalog, such as dashboards, dashboard pages, folders, and reports. You can view only the objects for which you are authorized. For example, a mid-level manager may not be granted access to a dashboard containing summary information for an entire department.

The Oracle BI repository development process adheres to the classic Software Configuration Management (SCM)process, which utilizes a three-way merge to manage concurrent development.
The merge process involves three repositories:
* The (Original|Received|Master|Parent) repository. The repository that you received before changed.
You must keep it preciously unchanged.
* The Modified repository. The repository that contains the customizations you made to the original repository.
* The Current repository. Generally, the repository that is in production and where some customisations could have been performed by other people.
In a multiuser environment (MUDE), Developers check out the file and make changes locally. Then, these changes are automatically reconciled and merged into the master repository.

Explanation
Download and installation of the client

The client install executable is available for download from the More Products menu in Oracle BI Interactive Dashboards and Oracle BI Answers.
See picture below.
http://gerardnico.com/wiki/_media/dat/obiee/moreproducts.gif

The Oracle Business Intelligence (BI) Administration Tool can be used to build,
modify, enhance, and manage an Oracle BI repository.
C: To add a new user to a repository
1 Open a repository in the Administration Tool.
2 Display the security manager by selecting Manage > Security.
3 Select Action > New > User to open the User dialog box.
4 Type a name and password for the user.
5 If you want to log queries for this user in the query log, change the query logging level to 1 or 2.
6 Click OK.
This creates a new user with default rights granted to it.
Note: What is Oracle BI Admin Tool/Oracle Business Intelligence Administration Tool?
Oracle Business Intelligence Administration Tool is Used to manage OBIEE server
Available only for Windows operating systems.
A Windows application that allows the BI Server administrator to create & edit repositories.
Can edit repositories in either online or offline mode.
Having a session manager and a cache manager in online mode.