@@ -37,11 +37,11 @@ through from the user.

 **Response**:

 ```

 {

-  "Err": null

+  "Err": ""

 }

 ```

-Respond with a string error if an error occurred.

+Respond with a non-empty string error if an error occurred.

 ### /GraphDriver.Create

@@ -51,22 +51,35 @@ Respond with a string error if an error occurred.

 {

   "ID": "46fe8644f2572fd1e505364f7581e0c9dbc7f14640bd1fb6ce97714fb6fc5187",

   "Parent": "2cd9c322cb78a55e8212aa3ea8425a4180236d7106938ec921d0935a4b8ca142"

+  "MountLabel": ""

 }

 ```

-Create a new, empty, filesystem layer with the specified `ID` and `Parent`.

-`Parent` may be an empty string, which would indicate that there is no parent

-layer.

+Create a new, empty, read-only filesystem layer with the specified

+`ID`, `Parent` and `MountLabel`. `Parent` may be an empty string,

+which would indicate that there is no parent layer.

 **Response**:

 ```

 {

-  "Err: null

+  "Err": ""

 }

 ```

-Respond with a string error if an error occurred.

+Respond with a non-empty string error if an error occurred.

+

+### /GraphDriver.CreateReadWrite

+

+**Request**:

+```

+{

+  "ID": "46fe8644f2572fd1e505364f7581e0c9dbc7f14640bd1fb6ce97714fb6fc5187",

+  "Parent": "2cd9c322cb78a55e8212aa3ea8425a4180236d7106938ec921d0935a4b8ca142"

+  "MountLabel": ""

+}

+```

+Similar to `/GraphDriver.Create` but creates a read-write filesystem layer.

 ### /GraphDriver.Remove

@@ -82,11 +95,11 @@ Remove the filesystem layer with this given `ID`.

 **Response**:

 ```

 {

-  "Err: null

+  "Err": ""

 }

 ```

-Respond with a string error if an error occurred.

+Respond with a non-empty string error if an error occurred.

 ### /GraphDriver.Get

@@ -109,7 +122,7 @@ Get the mountpoint for the layered filesystem referred to by the given `ID`.

 ```

 Respond with the absolute path to the mounted layered filesystem.

-Respond with a string error if an error occurred.

+Respond with a non-empty string error if an error occurred.

 ### /GraphDriver.Put

@@ -126,11 +139,11 @@ filesystem layer.

 **Response**:

 ```

 {

-  "Err: null

+  "Err": ""

 }

 ```

-Respond with a string error if an error occurred.

+Respond with a non-empty string error if an error occurred.

 ### /GraphDriver.Exists

@@ -189,13 +202,13 @@ with the specified `ID`

 ```

 {

   "Metadata": {},

-  "Err": null

+  "Err": ""

 }

 ```

 Respond with a set of key/value pairs containing the low-level diagnostic

 information about the layered filesystem.

-Respond with a string error if an error occurred.

+Respond with a non-empty string error if an error occurred.

 ### /GraphDriver.Cleanup

@@ -210,11 +223,11 @@ unmounting all the layered file systems.

 **Response**:

 ```

 {

-  "Err: null

+  "Err": ""

 }

 ```

-Respond with a string error if an error occurred.

+Respond with a non-empty string error if an error occurred.

 ### /GraphDriver.Diff

@@ -252,7 +265,7 @@ Get a list of changes between the filesystem layers specified by the `ID` and

 ```

 {

   "Changes": [{}],

-  "Err": null

+  "Err": ""

 }

 ```

@@ -269,7 +282,7 @@ changed and `Kind` is an integer specifying the type of change that occurred:

 - 1 - Added

 - 2 - Deleted

-Respond with a string error if an error occurred.

+Respond with a non-empty string error if an error occurred.

 ### /GraphDriver.ApplyDiff

@@ -290,12 +303,12 @@ and `Parent`

 ```

 {

   "Size": 512366,

-  "Err": null

+  "Err": ""

 }

 ```

 Respond with the size of the new layer in bytes.

-Respond with a string error if an error occurred.

+Respond with a non-empty string error if an error occurred.

 ### /GraphDriver.DiffSize

@@ -313,9 +326,9 @@ Calculate the changes between the specified `ID`

 ```

 {

   "Size": 512366,

-  "Err": null

+  "Err": ""

 }

 ```

 Respond with the size changes between the specified `ID` and `Parent`

-Respond with a string error if an error occurred.

+Respond with a non-empty string error if an error occurred.