AT&T MERLIN LEGEND Release 3.0 Programming Summary Manual page 70

Type of Trunk
Separate sections cover "DS1 Facilities," "Tie Trunks," "DID Trunks," and "PRI
Facilities."
A slot is the physical location of the individual module on the control unit.
There is a maximum of 17 slots which are numbered as follows:
Basic carrier: slots 1 through 5
First expansion carrier: slots 6 through 11
Second expansion carrier: slots 12 through 17
A port is a line or trunk jack on the module. Individual modules support
different numbers of ports. On any module, port 1 is the lowest physical jack
position. Lines connect equipment to the switch and trunks connect a switch
to a switch. Lines and trunks have logical IDs, a unique numeric identifier for
each extension and trunk jack in the communications system control unit.
Lines are numbered from 1 to 144, while trunks are numbered from 801 to
880. An MLX extension port has 2 logical IDs per 1 physical jack.
5-2 Lines and Trunks