Changes start in the field: a hidden condition behind a wall, an RFI answer that adds scope, an owner request in a site walk, a design error. A change event is the record of that moment, created before anyone knows the price.
Logging early matters for three reasons. Contracts usually set notice requirements, often with tight time limits, and missing them can cost you the right to be paid. Early logging also shows the true exposure on the job: costs that are probably coming even though nothing is signed. And it keeps the story straight: which RFI, which drawings, which photos, which daily log.
Not every change event becomes an owner change order. Some are absorbed by contingency, some are back-charged to a sub, some turn out to be in scope. The point of the event is to make that decision deliberately instead of by accident.
Sample data: on Riverside Medical Center, the super finds missing fire dampers behind a hidden condition. That becomes RFI-212, then a change event, then eventually CO #14. The money is decided later. The record starts now.