Hello,
Because I have read PMPOK 5th Ed. in that time there only an output for some processes
after we have obtain the approval of Project Management Plan with baselines( at Execution and (C&M) phases).
In that time if we need to make a change request we go to ( Perform integrated change request and do it).It is pretty good and understandable.
In PMBOK6th Ed We I have corrected my understanding that Not only after getting approval for the plan of (Project Management Plan), but after we obtain the baselines even if the process is still initial or plan phases but this process usually defined after we obtain the baselines I can raise a change request just like ( 13.1 Identify Stakeholders or 6.2 Define Activity or 11.5 Plan Risk Responses or 12.1 Plan Procurement management )
In Summary building baselines are very critical and if you are going to change it then change request should take over.
Due to above it will add more pain for predictive life cycle projects.