uboot_overlay_addr4=/lib/firmware<|file4>.dtbo

hello, on line of the uEnv.txt is uboot_overlay_addr4=/lib/firmware<|file4>.dtbo.
Who can tell me the name of ? Or how can i find out which name and where I can find the source?
thanks’s

https://github.com/beagleboard/bb.org-overlays/tree/master/src/arm

Otherwise, what cape did you plug in?

Regards,