Redlining is the process of comparing two datasets and displaying the changes in a meaningful and human readable way. Comparing XML files and rendering the results is more complex than just identifying the differences between two files. Using the experiences of International Organization for Standardization (ISO) as a case study, this paper will describe the process of comparing two versions of a JATS XML file, filtering out changes that have no meaningful impact (e.g. changes in tag order of article-id tags) and ignoring changes that the business requirements deem trivial. The paper will go on to identifying and rendering changes to content ranging from simple paragraphs, tables, equations, figures and lists. The case study will cover how differences are rendered in a way where the reader can easily understand and follow the changes. The paper will describe the easy wins, the difficulties and impossibilities of a JATS XML redlining workflow. The paper will conclude with what changes can be made to process and content structure to make redlining more effective.