It sounds like you’re referencing a specific build string or artifact name, something like:

: Version 7.2.1 is part of the 7.2 "Feature" branch. If you are looking for maximum stability for a production environment, Fortinet typically recommends the "Mature" branch (e.g., 7.0.x or specific later 7.2.x builds).

Acting as a boundary firewall for hypervisor clusters (Proxmox, KVM).

The technical string refers explicitly to a highly specialized virtual appliance deployment file: the FortiGate-VM64 for Linux KVM, running FortiOS version 7.2.1 (Feature/F-Release), Build 1254 , packaged as a QEMU Copy-On-Write ( .qcow2 ) virtual disk image.