For use u7z you must add following line to extfs.ini

=-=-=-=-=-= Cut -=-=-=-=-=-
u7z
=-=-=-=-=-= Cut -=-=-=-=-=-

And add somthing like this to extension file

REMARK: 7z may be replaced with 7za

=-=-=-=-=-= Cut -=-=-=-=-=-
regex/\.(7z|7Z)$
	View=%view{ascii} 7z l %f
	Open=%cd %p#u7z
=-=-=-=-=-= Cut -=-=-=-=-=-

This must be added before Manual pages Lines to prevent handle 7z archive
like man page


If you have installed 7z with plugins, you can view and unpack .cab and other
(if there is plugin) archive types with u7z, just add

=-=-=-=-=-= Cut -=-=-=-=-=-
regex/\.(cab|CAB)$
	View=%view{ascii} 7z l %f
	Open=%cd %p#u7z
=-=-=-=-=-= Cut -=-=-=-=-=-

to extension file, and somthing like this for other supported archives.