Site changes were one of the things I had a hard time understanding too when I first joined RR. Those changes are not always readily visible if you don't know what you're looking for. There are several fields an Admin can change or edit that would be noted as a site change. Like Al said, it could be as simple as adding, deleting, or editing a frequency on that particular site in the system frequencies box. Additionally, if you click on the hyperlink for a particular site, you will see a popup box that contains lots of additional information for a TRS site, like its site number, county that the site is in, its FCC call sign, and location, among others. Some of that information is only useful to those programming professional two way radios. Many times, you can determine what an admin changed in a site by investigating that popup. Hope we've answered your question!