The hold is the predessor to the actual debit which will occur when the "item" is presented. As I recall, the initial query comes in for $X and is serial numbered. That authorization is the hold. Then the transaction itself comes in and clears as it matches the serial number.
There is no hold to disclose, per se, as the debit is on its way and those funds are committed. It isn't a Reg. E or CC issue.
the process may be explained in your Reg. E disclosures, but there is no individual notice by transaction.
Opinions stated are not necessarily that of my employer.