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+# Internal Qt protocol extensions
+
+The protocol extensions in this folder are considered implementation details of
+Qt. I.e. they may removed, renamed or changed without warning.
+
+## Suffixed  protocols
+
+For protocols that have a version suffix, however, we will strive to not break
+backwards compatibility without bumping the suffix (renaming the protocol).
+E.g.: If your client sees a `zqt_key_v1` global, it can safely bind to it:
+the key event will always take the same number of arguments, regardless of
+compositor version.
+
+This is important also within a Qt-only scope if there are multiple versions of
+Qt on the system. Consider for instance an application statically linked to Qt
+(such as Qt Creator) running against a Qt compositor installed by the distro).
+In such cases we don't want the compositor and client to disagree on the
+protocol definition.