The "Process Holding Tank now" link will process ALL all selected blocks with the "Holding" status older than the "Holding Tank Days" setting, and change them to the "Available" status.
The The default time for blocks to be held prior to showing the in holding tank is 30 days, but this number is customizable from the IPAM Configuration page.
While in the Holding Tank, you may open the IPAM Manage page for a specific block by clicking on the block's CIDR - this allows you to review the block or manually manage it otherwise.
Regardless of the holding tank days setting, blocks may be manually reset to available at any time.
Select individual blocks to release from holding by clicking the checkbox for the desired block(s), then click "Process Holding Tank".
To release all blocks from the Holding Tank, click the "select all" checkbox at the top left header of the table, ensuring all blocks are selected, then click "Process Holding Tank".
When an administrator elects to process the Holding Tank, it will show the information above.