Begin milestone 3 age persistence

README.md

@@ -62,15 +62,17 @@ The built mod is written to `build/libs/`.
 
 ## Versioning
 
-Rivencraft versions use `x.y.z`:
+Rivencraft versions use `x.y.z.b`:
 
 - `x` changes for a major public release.
 - `y` changes when a development milestone is completed.
-- `z` changes for iterations within the current milestone and for bug fixes.
+- `z` changes for each release slice within the current milestone.
+- `b` changes for bug fixes and additional work within that release slice.
 
-The patch component resets to zero when a milestone is completed. For example,
-milestone 2 development follows `0.1.1`, `0.1.2`, and so on; completing that
-milestone produces `0.2.0`.
+The build component resets to zero when a new release slice begins. Completing
+a milestone increments `y` and resets both `z` and `b` to zero. For example,
+milestone 2 development can progress from `0.1.1.0` to `0.1.1.1`, then
+`0.1.2.0`; completing the milestone produces `0.2.0.0`.
 
 ## Porting approach