I've been struggling with a formalized standard for change tracking and commenting in plain text.1 I don't have any conclusions, but I have found some very cool tools.
Brat is a web app for doing extremely complex markup of text. It's a tool for marking entity definitions and relationships and has its roots in the sciences where relationships between words tell a greater story than the single sentence may convey.
Diff tools work well for reviewing edits, but they are not so great with text-bound comments and more subtle punctuation changes. ↩