2.That portion of a message terminated by an EOB or ETB line-control characteror, if it is the last block in the message, by an EOT or ETX line-control character.
6.A short block of data of fixed length and destination information. It is the unit in which information(a message) is transferred in a packet-switching network. Packets may consist of as many as8000 bits, and more from noder to node in the network.
8.In cryptography,the additional characters added to a plaintext message,to ensure that its length is an integral number of blocks for encryption by a block cipher.