There are two options to use Renewal function:

Default: This option uses normal Renew SIP messages (29-30 and 65-66 message pairs). Always use this if the library system supports these messages.

Use check out: This option creates separate Check in messages and Check out messages for all renewed items. It can be used if the library system does not support the standard renew messages. Note: this may not work as expected, as the check in and check out messages arrive in very quick succession, and not all systems allow that.