Ok, we all know that routers don't reboot, right? Specially with the enhanced infrastructure in XR 6.0.0 which runs all control plane as a container on top of a Linux kernel. However, stuff happens. Operator error or some catastrophic event takes place and the worst happens. How to find out the reboot history? There's a simple model that provides that info: Cisco-IOS-XR-linux-os-reboot-history-oper. Equally simple, see an sample app to read the reboot history and produce human readable output similar to the "show reboot history" command. Give it a try! (but don't reboot your box to test it :-) )
As usual, take a look at the README file for basic apps. It explains how apps are named and how to run them.