The Access Control List function of Joomla controls which part of the content users are able to see or which actions they can take.
The restrictions are applied for groups, each group can be thought of as a role that a user will have within the website. Keep in mind that one user can be a member of one or more groups within Joomla. If desired, groups can have parent groups. In this case, they automatically inherit the Access Levels of the parent group.

Reverse Auction Factory comes with its own implemented ACL system, that uses Joomla groups, and can assign them to either Bidders or Sellers, having automatically set restrictions for accessing various pages of the component or taking certain actions. With this feature configured, when a user wants to visit a specific page, the system checks the permission for this combination of user and action. If it is allowed, then the user can proceed. Otherwise, the action will not be allowed.

Upon installing the component, you will need to follow some simple steps in order to have a fully operational ACL system and to separate bidders from sellers.

First and foremost, you will need to create specific groups for them.

• 1. From Joomla's Administrator Menu, go to users and choose Groups section to define Bidders and Sellers groups.
  

There, add at least two new groups, preferably with the names "Bidder" and "Seller", but you can add what suits better on your website.
Group Parent for both of them must be Registered.

• 2. Define two new Viewing Access Levels for the newly created groups.
  

First access level:
Level Title - Bidder
AND check 'Bidder' in the list 'User Groups Having Viewing Access'.
Second access level:
Level Title - Seller
AND check 'Seller' in the list 'User Groups Having Viewing Access'.

• 3. From Joomla's Administrator menu go to Menus/Menu Manager and click on Reverse Auction Factory MENU. ((!) this is an optional step which will hide some menu items that can't be used by all groups)

Set access level group to 'Bidder' for menu items: 'Watchlist', 'My Bids'.
Set access level group to 'Seller' for menu items: 'New offer', 'My auctions'.
You can leave 'Auctions', 'Auctions on map', 'Search', 'Categories' and 'Profile' with Public access or only for Registered, as you consider.

• 4. From Reverse Auction Factory's menu go to Settings/General Settings and click on the ACL tab to set Auction menu item access for groups:

On the 'Bidder Groups' click on 'Bidder' to choose this from the list of available groups.
Do the same for 'Seller Groups' by choosing 'Seller'.
Afterward, click on 'Save'.

In the administration area of Reverse Auction Factory, you can find the Users list, with basic user information and management.

Registration is handled by Joomla. Users then have to fill in a Reverse Auction profile to use the auctioning system. Until the Reverse profile is filled, whenever attempting to access Reverse Auction menus, users will be redirected to the profile filling page. (for example, when attempting to post an auction)
Viewing an auction does not require a user profile, or even logging in.

Here you see their email, country, username, along with the Status and Ranks. The Block/Unblock column allows you to ban that user from the Joomla Login, and incidentally from Auction related actions.

Users with Verified and Powerseller ranks can receive differential prices for the Payment items. These prices are set in the config of each payment plugin.

Clicking on a name will take you to the details page of the respective user.
On the details page, you can see all the details that the user has provided (including custom fields), along with a few auction details and the user balance (the balance used for RAF payment plugins).

(!) Documentation based on Reverse Auction Factory version 4.3.5