diff --git a/3.4.-pri-request=stations_available.md b/3.4.-pri-request=stations_available.md
index 318c9ce..715a51a 100644
--- a/3.4.-pri-request=stations_available.md
+++ b/3.4.-pri-request=stations_available.md
@@ -29,7 +29,7 @@ Groups are identified by ID. The following groups of bicycles are defined:
 | ------ | ------ |
 | 300101 | Cargobike |
 | 300103 | Citybike |
-Keep in mind, each ID is preceded by an operator-prefix.
+Keep in mind, each ID is preceded by an operator-prefix. Datatype is array, because each station can have more byke_group 
 
 Example
 **REST request=stations_available** for authorized users