MyBB 1.8.18 Pre-Release

[effone]

It is minor, as per semver. See:

A normal version number MUST take the form X.Y.Z where X, Y, and Z are non-negative integers, and MUST NOT contain leading zeroes. X is the major version, Y is the minor version, and Z is the patch version. Each element MUST increase numerically. For instance: 1.9.0 -> 1.10.0 -> 1.11.0.

https://semver.org/#spec-item-2

MyBB is partially adapted the version system and will be following completely in future, I guess.