versioning

docs/semantics.md

@@ -2,6 +2,16 @@ This document defines the semantics of a gcsfuse file system mounted with a GCS
 bucket, including how files and directories map to object names, what
 consistency guarantees are made, etc.
 
+# Compatibility
+
+The following compatibility constraints are worth noting:
+
+*   gcsfuse does not support GCS buckets with [object versioning][] enabled.
+    (The default is to have this disabled.) No guarantees are made about its
+    behavior when used with such a bucket.
+
+[object versioning]: https://cloud.google.com/storage/docs/object-versioning
+
 
 <a name="caching"></a>
 # Caching