In other cases, however, it is not. If blocks are commonly as small as five or ten bytes, then most of the cross-net data will be control information. The BM option is intended as a simple data compression technique, to remove this overhead from the communication channel. Description of the option The option is enabled through the standard Telnet Option negotiation process. Except for the ability to refuse particular definitions, the receiver of data has no control over the definition and use of mappings.
Data are to be interpreted only as their normal character values.
Expanded strings are not subject to reinterpretation, so that recursive definitions cannot be made. In particular, they may NOT begin outside a macro and continue or terminate inside one, since no macro replacement takes place while processing any Telnet command. IAC interpretation is not over-ridden during BM subcommands so that IAC SE will continue to safely terminate malformed subcommands.