diff --git a/docs/SUMMARY.md b/docs/SUMMARY.md
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--- a/docs/SUMMARY.md
+++ b/docs/SUMMARY.md
@@ -8,6 +8,7 @@
 ## Usage
 
 * [Installation](usage/installation.md)
+* [Interface](usage/interface.md)
 * [Methods](usage/methods.md)
 * [Scopes](usage/scopes.md)
 * [Fallback locale](usage/fallback-locale.md)
diff --git a/docs/usage/interface.md b/docs/usage/interface.md
new file mode 100644
index 00000000..bbaf2e9d
--- /dev/null
+++ b/docs/usage/interface.md
@@ -0,0 +1,21 @@
+# Interface
+
+The package provides and interface `\Astrotomic\Translatable\Contracts\Translatable` which describes the public API. It could be that the trait defines more public methods but they aren't part of the defined public API and won't force a new major release if changed or removed.
+
+In addition to the interface we rely on the following methods which will, if changed or removed, also trigger a new major release.
+
+## protected Interface
+
+```php
+interface TranslatableProtected
+{
+    // detect if a given translation attribute value is empty or not
+    protected function isEmptyTranslatableAttribute(string $key, $value): bool;
+    
+    // save all attached translations
+    protected function saveTranslations(): bool;
+}
+```
+
+
+