RID Lookup on table with one column?

This is a simplification of a real cursor query:

DECLARE @T table (a int NOT NULL INDEX ia UNIQUE);  INSERT @T (a) VALUES (1), (5), (25), (75);  DECLARE c CURSOR LOCAL      SCROLL DYNAMIC OPTIMISTIC TYPE_WARNING FOR SELECT T.a FROM @T AS T ORDER BY T.a ASC FOR UPDATE OF a;  OPEN c;  FETCH RELATIVE 2 FROM c;  CLOSE c;  DEALLOCATE c; 

The execution plan for the FETCH shows an RID Lookup:

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I am having trouble understanding how this plan produces the result specified by the statement:

FETCH RELATIVE 2 FROM c; 

I am most puzzled by the RID Lookup because the table has only one column, and that is returned by the Index Scan.

A detailed explanation of how the plan works would be most appreciated.