Extended Access options help you to prevent turnaways when owned Non-Linear, 3-user and 1-user titles are in use. 

Extended Access is a set of rules on how to handle situations where there is maximum use on an owned title and another patron needs it. The library can pre-determine whether to initiate a just in time short-term loan, upgrade, or purchase another copy. So rather than turning the patron away, the access can be granted according to the pre-established rules. Alternatively, you may choose to mediate access to owned titles that are in use. 

You can find your Extended Access settings in LibCentral under Settings->Access Permissions. Click on the Permission ID for the Access Permission you would like to edit and select the Owned tab.

Non-Linear Expired Loan Days: 

The Non-Linear Expired Loan Days settings are used to control patron access to owned Non-Linear titles that have no annual loan days remaining. The loan days will reset annually on the purchase date. 
Extended Access Settings for Non-Linear Expired Loan Days. These are described below.

The settings available for Non-Linear Expired Loan Days are: 

3-user/1-user Turnaway Handling: 

The 3-user/1-user Turnaway Handling settings control how patrons access owned 3-user/1-user titles that have reached maximum concurrent use.
Extended Access Settings for 3-user/1-user Turnaway handling. These settings are described below.
The settings available for 3-user/1-user Turnaway Handling are:
Please note that Extended Access can only be applied if the title being accessed is still available for sale. If the title is no longer offered for sale, the user will be turned away.