EXFO FTB-1v2 Guia Del Usuario página 403

<INDEFINITE LENGTH ARBITRARY BLOCK RESPONSE DATA>

This data type is used by a device to return blocks of 8-bit binary
information when the block length was not predefined or when data
has to be computed later.
#
Note: If you receive a zero as the first digit (#0), it is necessarily followed by a
<RESPONSE PROGRAM MESSAGE TERMINATOR> so that you will detect
the end of the <INDEFINITE LENGTH ARBITRARY BLOCK RESPONSE
DATA>.
Example: #0<DAB><DAB><DAB><DAB><terminator> where
"<DAB>" stands for data byte.
FTB-1v2 and FTB-1v2 Pro
<8-bit data
0
Applicable Data Types for Output —IEEE 488.2
<RESPONSE MESSAGE
byte>
Data Types
TERMINATOR>
391