What does RTNL mean?

Question

I am looking at the Connection Manager (ConnMan) source code, which is a tool for Linux(-like) systems to manage networks. One of the (undocumented) source files has the vague naming rtnl.c. Does anybody know, what is meant with RTNL? Googling for it was not very effective. Every site that really is connected to networks and RTNL seems to be written by and for people who already know what it means.

Because in one answer there is some discussion about some different ConnMan sources, I am using the one available from:

git://git.kernel.org/pub/scm/network/connman/connman.git

Answer 1

If you look at the source it says it's for "Routing Netlink". The netlink manpage says " Netlink is used to transfer information between kernel and userspace processes."

The source for rtnl.c is only like 50 lines and it seems pretty obvious from reading it what it's for...