Structural (or development) editing
The central question when editing for structure is ‘Does this writing work?’. Is it achieving what it sets out to achieve? If not, structural editing can help to structure your thoughts more effectively. This is not about creating new content, only working with the existing text to make it more effective. This level of editing is not always necessary and very much depends on the context within which you are writing.
I edit a variety of content, primarily academic journal papers and curriculum content for schools and colleges. Copy-editing is about ensuring the syntax is smooth, grammatically correct and well punctuated (good punctuation can vastly improve readability!). I also ensure word choice is appropriate, that an appropriate style is used and check for consistency of headings, cross-references and any citations/references. A list of agreed style conventions or decisions is useful. Copy editing is not about changing the substance of the content and I will always raise queries where necessary.
Distinct from copy editing, proofreading is about checking the fine detail – ideally against the style sheet. Proofreading picks up typing errors, small grammatical mistakes, inaccuracies in page and heading numbering, fonts and text sizes. Even if your writing is of a high standard, the final result will always benefit from the eye of a good proofreader.