Apple Logic Pro 9 - Manual (Page 1121)

To create a monitor object
µ
Choose New > Monitor (or use the New Monitor key command).
Monitors are useful as both testing and branching devices. When coupled with objects
that have functionally different outputs (channel splitters and mapped instruments, for
example), monitor objects can be used to attach more than one output cable to the same
function.
Macro Objects
Macros are not actually Environment objects. Rather, they are collections of other
Environment objects and their cabling.
To create a new macro
µ
Select all Environment objects that you want to include, then choose New > Macro.
1121 Chapter 37 Environment Objects Reference