what would be the eqivalent of thsi blitz3d to bli

Correct, thats a TStream thing ;-)
Although, the code above definitely never worked ... thats a thing to guarantee. FileType assumes a path, readfile returns an int handle (not a string)

	local levdat:TStream=ReadFile("config.cfg")
	local level:int
	local levelsetname:string
	If levdat <> null
		levelsetname=ReadString$(levdat)
		level=ReadByte(levdat)
		CloseFile(levdat)

	endif
	levdat=WriteFile("config.cfg")
	WriteString(levdat,levelsetname$)
	WriteByte(levdat,level)
	CloseFile(levdat)