diff --git a/book/features/versioning.md b/book/features/versioning.md
index 6f0f55d..ed2a626 100644
--- a/book/features/versioning.md
+++ b/book/features/versioning.md
@@ -20,10 +20,11 @@ We have come up with guidelines how to use the two TeachBooks-versioning options
 3. Errata versions MUST be incremented if a small change is made which should be communicated to the reader in both the source code and in the book itself. If the small change is not crucial (like a simple typo), you might consider not defining it as a new version but combining it with other changes in the next errata or additions version.
 4. Additions version MUST be incremented if an addition is made to the book. It MUST be communicated in both the source code and in the book itself. It MAY include errata level changes. The errata version MUST be reset to 0 when the addition version is incremented.
 5. Academic year version MUST be incremented if a fresh book is started for which additions will follow later. It MUST be communicated in both the source code and in the book itself. Additions and errata versions MUST be reset to 0 when academic version is incremented.
-6. Precedence refers to how versions are compared to each other when ordered.
+6. A pre-release version MAY be denoted by appending `.pre-release`. Pre-release versions have a lower precedence than the associated normal version. A pre-release version indicates that the version is not complete.
+7. Precedence refers to how versions are compared to each other when ordered.
    1. Precedence MUST be calculated by separating the version into academic year, additions and errata identifiers in that order.
    2. Precedence is determined by the first difference when comparing each of these identifiers from left to right as follows: Academic year, additions and errata versions are always compared numerically. Example: 2024.0.0 < 2025.0.0 < 2025.1.0 < 2025.1.1.
-7. The way in which the version number is incremented after the initial release should be explained in the README of the source code and in the book itself.
+8. The way in which the version number is incremented after the initial release should be explained in the README of the source code and in the book itself.
 
 An example can be seen in [the source repository of the Engineering Systems Optimization book](https://github.com/TUDelft-books/CME4501/tags) showing tags for different versions.
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