AT&T Merlin II Installation And Maintenance Manual page 260

The unprotected mode must be used for the
NOTES:
E&M Type 1 Standard interface in order to
meet the voltage drop criteria for that interface.
Switch positions designated n/a can be either on
or off.
Refer to Form lb, System Form-Tie Lines and set the
options for each tie line port as described here.
3-52 Administering a New System