Reviewer Property Usage 
The Reviewer designating property is a special property used to identify the person or team that must review an activity performed by another user in a business process flow. This person or team member can approve or reject the action taken by the user. A reviewer can also reopen the previous step of a business process flow.
The Reviewer property must be defined prior to creating a BPF template, as the administrator is required to enter it during the setup of a business process flow template.
Features
When defining the property, the following rules apply:
The reviewer designating property can be set up on any dimension and can be any name, such as BPF1_Reviewer. A dimension can have one or more uniquely named properties.
You typically select a reviewer designating property when setting a drive dimension and owner property.
When defining the property values, the following rules apply:
The value can be a user ID or a team, or a combination of both.
If defining multiple property values, you must separate each entry by a comma.
A user ID must include its domain, as in domain\ID.
A team name must be enclosed in brackets, as in [TEAM].
The reviewer property is case sensitive.
The limit is 255 characters.
A reviewer can reopen the previous step of a business process flow. The step must be defined to allow reopen.
Activities
To define a reviewer property, open the dimension that you want to designate as the driver dimension of the business process flow, then add a Reviewer property. For more information about adding properties to dimensions, see Member Behavior Using Dimension Properties.
After adding the dimension property, add the desired property values using the rules above. See the Maintaining dimension properties section in Member Behavior Using Dimension Properties.
When creating a business process flow, choose Enable Reviewers, then set a Reviewer property when defining the step region criteria for a new step.