IN Good Documents Practices, First write SOP for SOP, Means write a SOP, inwhich define SOP formats, Patterns, sections e.t.c, and explain how to write SOP and what are main sections, pattern and section of SOP. So you can’t change the SOP format, if yoiu want to change SOP format , revise your SOP for SOP and then change SOP header.
well to write SOP for SOP you are very right.
Yes! Incase of any change in the SOP regarding Format or Change in wordings, a revision number will be given and at the end “reason for revision” should also be mentioned.