A document modification event management system for notification of specific edits made to electronic content items, and a method of determining the relevance of the modification. As an example, a first user may make an edit to a portion of a document. A second user may receive a notification of this edit if the system determines the edit was relevant to the second user. In addition, during review of an electronic content item, a reader may select a specific portion of content and view the modifications that have occurred to only the selected portion. These tools can provide collaborative document users the ability to more readily monitor document development and stay up-to-date with changes that are important to them.