Is there a question here?
IAM is basically a roadmap for heap's data pages.
Not just heaps.
In sql2005 onwards this has started allocating INCLUDE columns for non clustered index, BLOB and row over flow data etc as well.
Include columns aren't reflected in, nor do they affect IAM pages.
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)SQL In The Wild
: Discussions on DB performance with occasional diversions into recoverability
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