AT&T Merlin II Release 3 System Manual page 11

With the customized configuration, each line button accesses only one line, but
every line doesn't have to appear on each phone nor do the lines have to appear
on the same buttons on each phone. See Figure 2-3. This type of system
provides complete flexibility in line assignment; you can assign lines to any
available button on a phone, in any order you wish. See "Line Assignments in
Square Systems" in Section 3, "Reference," for more information.
For example, a customized square system in an automobile dealership could
have three local lines assigned to the phone in the service department, a WATS
line and a local line assigned to the phone in the parts department, and a private
line assigned to the manager's phone. The ability to customize line assignments
enables a company to respond to the specific phone requirements of each
department.
FIGURE 2-3 Example of a customized square (nonpooled) system.
Changing to a Square System
When changing from a pooled system to a square system, first remove all the
pools from the phones. If the pools are not removed, the phones will have non-
functioning pool buttons instead of the intended square lines. See the
description of pooled systems and "MERLIN II System Telephones" on the
following pages. Changing from a pooled system will disable the Automatic
Route Selection feature. See "Automatic Route Selection" in Section 3, for more
information.
MERLIN II
System Control Unit
Line Line Line
Line
C
B
A
Customized
D
Type of System 2-3