doc: update daletl data format

specification/daletl.md

@@ -4,8 +4,6 @@
 
 Daletl must be serialized as [MessagePack](https://github.com/msgpack/msgpack/blob/master/spec.md). All data transfer between server and client is done in this format.
 
-## Data representation
-
 ### Root
 
 Daletl root is array of tags. For convenience, we will use the json5 representation of the data.
@@ -18,7 +16,11 @@ Daletl root is array of tags. For convenience, we will use the json5 representat
 
 All tags specification is in [Tags](./tags.md).
 
-Each tag is array of 1-3 elements.
+Each tag may be one of three types:
+
+#### Data Representation
+
+##### As array of 1-3 elements
 
 1. Tag id
 2. Tag body (optional if argument not specified, if argument specified it must be null)
@@ -26,17 +28,17 @@ Each tag is array of 1-3 elements.
 
 Tag id is integer number.
 
-Body can be only a string, null, or an array of tags.
+Body can be only a string, null, array of tags or tag (equals to array of tags with 1 tag).
 
 Argument can be number or string.
 
-#### Heading example
+###### Heading example
 
 ```json5
 [1, "This is heading", 1]
 ```
 
-#### Unordered list example
+###### Unordered list example
 
 ```json5
 [
@@ -47,3 +49,37 @@ Argument can be number or string.
   ],
 ]
 ```
+
+##### As string
+
+String becomes element tag.
+
+```json5
+"Element"
+```
+
+equals to
+
+```json5
+[0, "Element"]
+```
+
+##### As array of tags
+
+If array not started with a number. The implication is that this turns into an “element” tag
+
+```json5
+["Element", [1, "Heading"]]
+```
+
+equals to
+
+```json5
+[
+  0,
+  [
+    [0, "Element"],
+    [1, "Heading"],
+  ],
+]
+```