fixes #7: allow arbitrary uint for extension point

README.md

@@ -422,17 +422,18 @@ Boolean-valued map literal, for implementations which do not use repeated keyset
 
 #### extension\*
 
-    +--------+--------+~~~~~~+======+
-    |  0xFF  |xxxxxxxx| uint | data |
-    +--------+--------+~~~~~~+======+
+    +--------+~~~~~~+~~~~~~+======+
+    |  0xFF  | uint | uint | data |
+    +--------+~~~~~~+~~~~~~+======+
 
-Specifies an extension type tag `xxxxxxxx`, followed by a `uint` length, followed by zero or more bytes of data.
+Specifies a `uint` extension point, followed by a `uint` length, followed by a number of bytes of data matching the length.
 
 Encoders are expected to provide an interface for a consumer to specify a serialisation and deserialisation mechanism for a given type of data.
 
 ```js
-SuperPackTranscoder.extend(
-  // extension point: 0 through 127
+let transcoder = new SuperPackTranscoder;
+transcoder.extend(
+  // extension point
   0,
   // detect values which require this custom serialisation
   x => x instanceof RegExp,
@@ -443,11 +444,6 @@ SuperPackTranscoder.extend(
 );
 ```
 
-The extension ranges are reserved as follows:
-
-* Extension points 0-127 are available for user-specified extension types.
-* Extension points 128-255 are currently reserved for future spec additions.
-
 
 ## Optimisations