ECU map random question

[Rob_the_Sparky]

Sitting there with Rover gauge looking at the map and can't help wondering why nearly half the entries on the ECU fuel map are below idle, and are nearly identical. I'm surprised that so much of the map is dedicated to revs this low, especially when there is almost no difference between them. I would have thought you want more detail in the map where you use it.

Any experts out there that can enlighten me in my pondering?