diff --git a/protocol-spec/account-login-by-username.md b/protocol-spec/account-login-by-username.md
index cec0e6d..8874e4d 100644
--- a/protocol-spec/account-login-by-username.md
+++ b/protocol-spec/account-login-by-username.md
@@ -89,7 +89,7 @@ interface LoginRequestPayload {
 ```typescript
 interface LoginResponsePayload {
     /**
-     * Authentication token which required for various user actions (UUID)
+     * Authentication token which required for various user actions (static SHA256 hash string from 4096 random characters)
      */
     authToken: string,
 
@@ -99,4 +99,4 @@ interface LoginResponsePayload {
      */
     deviceID: string
 }
-```
\ No newline at end of file
+```
diff --git a/protocol-spec/account-registration.md b/protocol-spec/account-registration.md
index f2d8dd3..2e981ea 100644
--- a/protocol-spec/account-registration.md
+++ b/protocol-spec/account-registration.md
@@ -16,7 +16,7 @@ This extension is intended for creating user accounts on a server
 
 ## Use cases
 
-### Basic registration flow (with CAPTCHA)
+### Basic registration flow
 
 - Client:
 
@@ -80,7 +80,7 @@ interface RegistrationRequestPayload {
     /**
      * The username that the user wants to register
      */
-    username: string,
+    username?: string,
 
     /**
      * Array of user third party IDs (email and/or MSISDN)
@@ -90,7 +90,12 @@ interface RegistrationRequestPayload {
     /**
      * Password of new account
      */
-    password: string
+    password: string,
+
+    /**
+     * Login to freshly created user account when registration will be completed
+     */
+    loginOnSuccess: boolean
 }
 
 interface ThirdPartyID {
@@ -113,6 +118,11 @@ interface RegistrationResponsePayload {
     /**
      * ID of user (Username in priority. If we haven't username, then we put to this field one of user's third party IDs)
      */
-    userID: EntityID
+    userID: EntityID,
+
+    /**
+     * Property with login payload (can be omit if property loginOnSuccess wasn't indicated true in RegistrationRequestPayload)
+     */
+    loginPayload?: LoginResponsePayload
 }
 ```
diff --git a/protocol-spec/core.md b/protocol-spec/core.md
index d3f7165..3cadefb 100644
--- a/protocol-spec/core.md
+++ b/protocol-spec/core.md
@@ -3,6 +3,9 @@
 - [Protocol Core](#protocol-core)
   - [Transport](#transport)
   - [Entity ID](#entity-id)
+    - [Server-part](#server-part)
+    - [Username/Room alias/RoomID](#usernameroom-aliasroomid)
+    - [Special business rules](#special-business-rules)
   - [BaseMessage](#basemessage)
 
 ## Transport
@@ -16,18 +19,20 @@ For starting we simply use JSON + Websockets.
 - User ID with any 3PID: `%<type>:<data>@<serverpart>`
   - Currently supported only following types: `email` and `msisdn`.
 - Raw User ID: `@<UUID>@<serverpart>`
-- Message ID: `&<uuid>@<serverpart (from which server the message was sent)>`
+- Message ID: `&<uuid>@<serverpart (of source server)>`
 - Room ID: `!<roomID>@<serverpart>`
 - Single server-part: `<serverpart>`
 
-**Server-part**:
+### Server-part
 
 - hostname: `IPv4 / [IPv6] / dns-domain:<port (1-65535)>` (for end-users use)
-- server ID: static SHA256 hash string from 4096 characters (for internal protocol use) 
+- server ID: static SHA256 hash string from 4096 characters (for internal protocol use)
 
-**Username/Room alias/RoomID** - MUST NOT be empty, and MUST contain only the characters `a-z`, `0-9`, `.`, `_`, `=`, `-`, and `/`.
+### Username/Room alias/RoomID
 
-**Special business rules**: 
+MUST NOT be empty, and MUST contain only the characters `a-z`, `0-9`, `.`, `_`, `=`, `-`, and `/`.
+
+### Special business rules
 
 - RoomID SHOULD be UUID identifier.
 - Servers MUST use server ID in internal purposes instead of normal server-part with hostname. Only end-users MUST use normal server-part with hostname. This is done for easy multi-domain serving.
@@ -60,10 +65,15 @@ interface BaseMessage {
     to: EntityID,
 
     /**
-     * Operation success indicator (used to determine if the error happened while processing request)
+     * Operation success indicator (used to determine if the error happened while processing request) - MUST be only in response from server
      */
     ok: boolean,
 
+    /**
+     * Authentication token string (can be omit if the action does not require user authentication) - MUST be only in request messages from client
+     */
+    authToken?: string,
+
     /**
      * Message payload (used to store extra information in message, list of permissible fields in the payload depends on "type" field)
      */