Add some statement to Locking.

Documentation-develop/PROTOCOL.md

@@ -484,6 +484,9 @@ Server Response
 ### Record lock
 
 Request, extend or release a lock for a record, identified by the SIP. The SIP contain a SIP_FORM and a SIP_R (record id).
+
+See `Documentation-develop/diagram` for a state diagram.
+
 To detect record change at time of 'record lock' or 'record save', a MD5 hash is provided from the server
 and needs to pass back to dirty.php as well.
 
@@ -497,6 +500,7 @@ URL Parameters
 :  `s=<SIP>`   (form, r)
 :  `action=lock`, `action=extend`, `action=release>`
 :  `recordHashMd5=<value of hidden form element 'recordHashMd5'>`
+:  `tabUniqId=<unique id>`
 
 Server Response
 :	The response contains an [Lock Response].
@@ -509,7 +513,7 @@ JSON Response from the server (extended [Minimal Response]) containing:
 :	{
 :		"status": "success"|"error"|"conflict"|"conflict_allow_force",
 :		"message": "<message>"e5
-:    }
+:   }
    
 `status` indicates how the request has been fulfilled by the server. 
 On`"success"`, the Client display nothing to the user. 
@@ -520,11 +524,18 @@ On `"conflict_allow_force"` the Client opens the alert non-modal (default).
 
 ### tabUniqId
 
-Every tab get's a uniq id (timestamp) on page load: window.name.
-This 'tabUniqId' is saved in dirty record on lock acquire. 
-On page reload, when the 'release' comes after 'acquire' (unwished async behaviour), the locking is skipped (if same user 
-session) - on reload there is no variable 'tabUniqId'. On real lock acquire, the tab ID is compared and will be denied 
-if not matching. The 'tabUniqId' might not work in IE - doesn't matter: it's a seldom special situation.
+* Client: Every browser tab get's a `tabUniqId` (timestamp) as soon as the first time a lock is requested (acquire). 
+  This `tabUniqId` remains, until the tab is close. It is saved in window.name.
+  
+* Server: On lock request, the `tabUniqId` is saved in dirty record.
+ 
+  * The `tabUniqId` helps to implement 'optimistic locking': if there is no argument against 'grant lock' - grant it.
+    Example: In browser tab 'A' a lock is requested. For unknown reason, there is a stale lock for the
+    user session and the given tab id: grant the log. 
+     
+  * Unexpected async behaviour in client: On page reload (F5), the 'lock release' might come after 'lock acquire'. 
+    The form goes in 'read only' mode - an additional page reload (F5) solves the situation - but this is boring.   
+  
 
 ### Drag And Drop (sort)