Dear Mukts

As per my knowledge no such trigger exists at Block Level. here are the list of On-triggers
On-Check-Delete-Master
On-Check-Unique
On-Clear-Details
On-Close
On-Column-Security
On-Commit
On-Count
On-Delete
On-Error
On-Fetch
On-Insert
On-Lock
On-Logon
On-Logout
On-Message
On-Populate-Details
On-Rollback
On-Savepoint
On-Select
On-Sequence-Number
On-Update

Hi

on-clear-block Trigger is an master detail trigger when Master-detail relation block is created and when the master block is cleared on-clear-block trigger will fire and its functionality is dependent upon the Co-ordination properties of Master-detail block.