diff --git a/src/rest-api/auth.md b/src/rest-api/auth.md
index a3fc052..d91b936 100644
--- a/src/rest-api/auth.md
+++ b/src/rest-api/auth.md
@@ -122,6 +122,7 @@ POST `/auth/new_device/authorize` is used with two arguments:
 	- If new device token is incorrect, does not exist of expired, 404 error is returned
 - `device` is the device name.
 	- If the name already taken, random suffix will be added.
+	- Name SHOULD only contain `[^a-zA-Z0-9]`. All other symbols will be replaced with `_`
 
 ```mermaid
 sequenceDiagram
@@ -151,4 +152,5 @@ POST `/auth/recovery_token/use` to use the token. Two required arguments:
 - `token` is the recovery token
 	- If recovery token is incorrect, does not exist of expired, 404 error is returned
 - `device` is the device name
-	-  If the name already taken, random suffix will be added.
\ No newline at end of file
+	-  If the name already taken, random suffix will be added.
+	- Name SHOULD only contain `[^a-zA-Z0-9]`. All other symbols will be replaced with `_`
\ No newline at end of file