what are 4th files in /boot

[michaelgo]

what are .4th files in /boot directory?
thanx

[Patrick M. Hausen]

They implement the FreeBSD boot loader which is written in the Forth programming language.

More precisely they implement the deprecated boot loader. The current replacement was written in Lua.
Reason: there were in the end about two persons on this planet who understood the Forth loader. Whenever they attended the same conference other members of the FreeBSD core team got rather nervous.

See "bus factor"  ;)

They will probably disappear with 22.1 or 22.7 when the Lua loader is pulled in.