3Com 56k User's Manual And Reference page 57

Yn Selects power-on/reset default
configuration
Y0 Use profile 0 setting in
NVRAM
Y1 Use profile 1 setting in
NVRAM
Y2 Use factory configuration 0
(&F0)
Y3 Use factory configuration 1
(&F1)
Y4 Use factory configuration 2
(&F2)
Technical Reference
Z Resets modem
Z0 Resets modem to profile
selected by Y command
Z1 Resets modem to profile 0
Z2 Resets modem to profile 1
Z3 Resets modem to factory default
profile 0 (&F0)
Z4 Resets modem to factory
default profile 1 (&F1)
Z5 Resets modem to factory default
profile 2 (&F2)
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