Help with timing table

[riche]

I apologize for asking this question, I probably should understand it better and I think I do but here it goes.
If kpa is atmospheric pressure, and I understand that vacuum is measured in inches. They are to different things yet vacuum (as the engine is changing rpm) is directly affecting the atmospheric pressure correct?

So when you say my cam makes less vacuum and has a small rpm window it is more like saying I just eliminated a portion of the map bc my cam will not change or make vacuum at certain rpms?

I think I understand what you are saying I rarely see my engine in the lower portion of the table unless like you say I let off the gas during decel. Just want to make sure I understand why.