Talk:LXD/What are subuids and subgids?
The content of this article is attached to LXD by misunderstanding. Actually, when you setup LXC container all of the same are applicable. And lxc is a separate ebuild - http://gpo.zugaina.org/app-emulation/lxc
Nesting is not mentioned «User namespaces can also be nested but the nested namespace can only map ids that exist in its parent, so you can only reduce but not expand the id space by nesting.»
subuids and subgids are mentioned in https://man7.org/linux/man-pages/man7/user_namespaces.7.html
docker daemon have a special key, which is in manpage
--userns-remap=default|uid:gid|user:group|user|uid Enable user namespaces for containers on the daemon. Specifying "default" will cause a new user and group to be created to handle UID and GID range remapping for the user namespace mappings used for contained processes. Specifying a user (or uid) and optionally a group (or gid) will cause the daemon to lookup the user and group's subordinate ID ranges for use as the user namespace mappings for contained processes.