Notifies peers about the existence of some information (block or transaction) Based on selected services in the VERSION message, INV messages may not be sent.
If a bloom filter has been sent to this node via FILTERLOAD, transaction INVs will only be sent if they match the bloom filter.
|compact int||4 bytes||32 bytes||...||4 bytes||32 bytes|
|vector size N of||type 1||hash 1||type N||hash N|
NOTE: Since a block header is a relatively small data structure, and block propagation speed is an important network metric, a peer may send HEADER messages in place of INV messages when a block arrives.
The type of the object that is available.
|3||Filtered Block (partial block with merkle proof)|
|5||Xthin block (Bitcoin Unlimited)|
|6||Graphene Block (Bitcoin Unlimited)|
The hash identifier of the available object.