diff --git a/docs/API/content-type/creating-co.md b/docs/API/content-type/creating-co.md
index 24dcc092..a9ff87d9 100644
--- a/docs/API/content-type/creating-co.md
+++ b/docs/API/content-type/creating-co.md
@@ -32,6 +32,7 @@ to the supporting endpoint `https://api.flotiq.com/api/v1/content/{name}`
 
 !!! note
     You can send custom `id` in the object data to assign a particular `id` to the object.
+    Id must match a regular expression `^[a-zA-Z0-9-_.,:=!#$%&(\`\’\{\}\" ]*$`.
     Random `id` will be assigned when the `id` property is not present in the object.
 
 !!! note