For most environments, an asynchronous map setting of zero achieves maximum throughput.
The value must be a 32-bit hexadecimal number.
The PPP protocol supports the replacement of nonprinting ASCII data in the PPP stream. These characters are not sent through the line, but instead are replaced by a special set of characters that the remote site interprets as the original characters.
The PPP asychronous map is a bitmap of the characters meant to be replaced. The lowest-order bit corresponds to the first ASCII character NUL, and so on.