Why does getdata have a field for the number of inventory entries? After a node receives an inv message, you can get the data for each tx/block hash using getdata:


  getdata - Request a single block or transaction by hash.


So if you can only get one tx or block at a time, what's the purpose of having a field in the getdata message for the number of entries you are requesting?


Field Size  Description   Data type   Comments
----------  ------------  ----------  -------------
?           count         var_int     Number of inventory entries
36x?        inventory     inv_vect[]  Inventory vectors





https://wiki.bitcoin.com/w/Network#Messages
https://en.bitcoin.it/wiki/Protocol_documentation#getdata
The documentation you are linking too is wrong, the bitcoin developer reference indicates you can send multiple inventories inside of a GetData message.