Apple Express Fax/Modem - Manual (Page 146)

&X n Synchronous clock source Ignored. Always returns OK. The modem
does not support synchronous modes.
&Y n Specify start-up profile Allows choosing between two different
configurations at start-up.
0 Specifies saved profile 0 as start-up configuration.
1 Specifies saved profile 1 as start-up configuration.
&Z n=s Store phone number
Stores the dial string s (64 characters maximum) in location n. The
value of n can be equal to 0, 1, or 2. Note that the dial string s is
constructed in the same fashion as the ATD command. It therefore must
be the last command on the command line and no other characters
should follow it in the dial string.
MNP-specific AT commands
\B n Send break Sends a break on the line for n times 100 milliseconds
( n ranges from 1 to 9).
%C n Compression enable Enables/disables MNP Class 5 data compression
during MNP reliable connections.
0 Disables data compression.
1 Enables MNP 5 data compression.
\G n DCE flow control Enables/disables modem-to-modem flow control.
Coupled with \X, it determines whether flow control characters are
passed through or filtered.
0 Disables modem-to-modem flow control.
1 Enables modem-to-modem flow control.
\N n MNP feature selection Determines whether MNP error control is used
in connections. The \N command setting also updates register S36.
The &Q command setting has precedence over \N command setting and
registers.
0-1 Normal mode MNP disabled.
2 Reliable mode The modem will interrogate the remote modem for
MNP capabilities. If the remote modem does not support MNP, the
local modem hangs up.
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