clarification with IDEC extensions

ii-doc.txt

@@ -32,10 +32,12 @@ and depend on the message contents hash (see the exact algorithm below).
 Station (node) HTTP API (as implemented in tii)
 -----------------------------------------------
 Every station must implement the following HTTP API calls.
+The tii codebase also implements some IDEC extenstions but they are entirely
+optional.
 In case of multi-line responses, the newline separator must be "\n" character
 (line feed, ASCII 10).
 
-- Fetching the public echo list (IDEC extension) -
+- Fetching the public echo list -
 
 Request: GET /list.txt
 Response: newline-separated list of echo_name:msg_count:echo_description
@@ -44,7 +46,7 @@ Note: msg_count must not decrease even if some messages are deleted.
 Some nodes (e.g. ii-php) still can violate this rule, so the message count
 reported by nodes still should not be the basis for any client-side logic.
 
-- Listing messages in the echo (s) -
+- Listing messages in the echo(s) -
 
 Request: GET /u/e/echo.1.name/echo.2.name/...
 IDEC extended syntax: GET /u/e/echo.1.name/echo.2.name/.../offset:count