Typically, the business component on which you set this user property is used expressly to provide a "My" view that restricts data by login (username) instead of position.
For example, the My Competitor business component exists primarily to provide the SI Com Tracked Competitors View in Siebel Briefings. This view is labeled as "My Tracked Competitors" in the UI, and it lists competitors that the user enters in his or her individual list.
The Employee Link user property on the My Competitor business component is set to a value of Employee/My Competitor. Competitor records that are associated with the user by the Employee/My Competitor link are the only records listed in the view.
You can inactivate this user property or modify its values. You should not create more than one instance of this user property for a business component.