Rockwell Automation Logix5000 Controllers I/O and Tag Data Programming Manual - Manual (Page 25)

Organize tags Chapter 2
When you create a tag, you define it as either a controller tag (global data) or a
local tag for a specific program (local data).
A Logix5000 controller lets you divide your application into multiple programs,
each with its own data. There is no need to manage conflicting local tag names
between programs. This makes it easier to reuse both code and tag names in
multiple programs.
Data at the program scope is isolated from other programs.
Tag scope
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