It is also known as baseline editing. It is just like editorial proofreading but here we process the spelling, grammar, punctuations, references, order of lists, other consistency etc

Here we perform all the process involved in light copyediting. Here we process style consistency, TOC entries, converting passive voice into active voice and etc.

Here we perform all the process involved in medium copyediting. The difference between medium and heavy copyediting is the level of judgment and rewriting involved. Here we process altering sentences to improve readability, Assigning new levels to heads to achieve logical structure and etc.