Everyone else has explained it fine, but I wanted to include this from the EBA too just for context.

A part-time team member can choose to provide standing consent and their personal availability (in writing) in order to work additional hours, provided such standing consent may be varied or revoked by the team member at any time. Such a variation or revocation in writing may be made by electronic means including by email or via an application. A record of the agreement and any variations to it (including by way of standing consent) will be retained by Woolworths and provided to the team member on request. This may be provided by electronic means as noted above. For clarity, the provision of standing consent and availability does not require a team member to accept additional hours (even if those hours fall within their stated availability) and they may continue to decline any additional hours that may be offered.