WikiFormatting
One of the most common types of editing for RecentChanges patrollers is to help people understand the simplicity of WikiSyntax (basic wiki formatting) over html. (WYSIWYG or WizyWig is a way to have formatting changes like word or other major applications. What you see is what you get. )
Examples
If some writes <b>Here is some bold text</b> and I change it to '''Here is some bold text''', I use the EditSummary: WikiFormatting.