It indicates compliance with the flammability standard defined by Underwriters Laboratories.
Raspberry Pi provides a full CM4 IO Board Schematic (PDF) which serves as the gold-standard reference for building your own carrier board. cm4 94v0 schematics
Dual HDMI interfaces, DSI display port, and CSI-2 camera interfaces. DSI display port
Power rail requirements (+12V, +5V, +3.3V, and global ground). and global ground).