Woah, new and esoteric indeed!
X.0.0 is experimental development
X.0.1 is pre-release stabilization stage
X.1.0 is the stable release
X.1.1 is development of release branch (fixes and backports)
X.2.0 is the second stable release
It looks like only X.1.0, X.2.0, etc uniquely tag a single point in the development history. Are all the others just moving labels?They switched the default C compilation mode from --std=gnu89 to --std=gnu11 in a bugfix-only release?
No, they did that in 5.1. The linked page is mostly about the overall 5.x series, with a tiny little section at the bottom about 5.2.
[1] https://gcc.gnu.org/develop.html#num_scheme