Update doc

lib/includes/nghttp2/nghttp2.h

@@ -748,7 +748,7 @@ typedef enum {
   /**
    * Indicates that END_STREAM flag must not be set even if
    * NGHTTP2_DATA_FLAG_EOF is set.  Usually this flag is used to send
-   * trailer header fields with `nghttp2_submit_request()` or
+   * trailer fields with `nghttp2_submit_request()` or
    * `nghttp2_submit_response()`.
    */
   NGHTTP2_DATA_FLAG_NO_END_STREAM = 0x02,
@@ -784,13 +784,13 @@ typedef enum {
  * :enum:`NGHTTP2_FLAG_END_STREAM` set, and
  * :enum:`NGHTTP2_DATA_FLAG_EOF` flag is set to |*data_flags|, DATA
  * frame will have END_STREAM flag set.  Usually, this is expected
- * behaviour and all are fine.  One exception is send trailer header
- * fields.  You cannot send trailers after sending frame with
- * END_STREAM set.  To avoid this problem, one can set
+ * behaviour and all are fine.  One exception is send trailer fields.
+ * You cannot send trailer fields after sending frame with END_STREAM
+ * set.  To avoid this problem, one can set
  * :enum:`NGHTTP2_DATA_FLAG_NO_END_STREAM` along with
  * :enum:`NGHTTP2_DATA_FLAG_EOF` to signal the library not to set
  * END_STREAM in DATA frame.  Then application can use
- * `nghttp2_submit_trailer()` to send trailers.
+ * `nghttp2_submit_trailer()` to send trailer fields.
  * `nghttp2_submit_trailer()` can be called inside this callback.
  *
  * If the application wants to postpone DATA frames (e.g.,
@@ -849,9 +849,9 @@ typedef struct {
  *
  * The category of HEADERS, which indicates the role of the frame.  In
  * HTTP/2 spec, request, response, push response and other arbitrary
- * headers (e.g., trailers) are all called just HEADERS.  To give the
- * application the role of incoming HEADERS frame, we define several
- * categories.
+ * headers (e.g., trailer fields) are all called just HEADERS.  To
+ * give the application the role of incoming HEADERS frame, we define
+ * several categories.
  */
 typedef enum {
   /**
@@ -1499,7 +1499,7 @@ typedef int (*nghttp2_on_stream_close_callback)(nghttp2_session *session,
  * NGHTTP2_HCAT_REQUEST``.  If |session| is configured as server side,
  * ``frame->headers.cat`` is either ``NGHTTP2_HCAT_REQUEST``
  * containing request headers or ``NGHTTP2_HCAT_HEADERS`` containing
- * trailer headers and never get PUSH_PROMISE in this callback.
+ * trailer fields and never get PUSH_PROMISE in this callback.
  *
  * For the client applications, ``frame->hd.type`` is either
  * ``NGHTTP2_HEADERS`` or ``NGHTTP2_PUSH_PROMISE``.  In case of
@@ -1511,7 +1511,7 @@ typedef int (*nghttp2_on_stream_close_callback)(nghttp2_session *session,
  * non-final response code and finally client gets exactly one HEADERS
  * frame with ``frame->headers.cat == NGHTTP2_HCAT_HEADERS``
  * containing final response headers (non-1xx status code).  The
- * trailer headers also has ``frame->headers.cat ==
+ * trailer fields also has ``frame->headers.cat ==
  * NGHTTP2_HCAT_HEADERS`` which does not contain any status code.
  *
  * Returning :enum:`NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE` will close
@@ -3255,7 +3255,7 @@ nghttp2_submit_response(nghttp2_session *session, int32_t stream_id,
 /**
  * @function
  *
- * Submits trailer HEADERS against the stream |stream_id|.
+ * Submits trailer fields HEADERS against the stream |stream_id|.
  *
  * The |nva| is an array of name/value pair :type:`nghttp2_nv` with
  * |nvlen| elements.  The application is responsible not to include
@@ -3274,26 +3274,26 @@ nghttp2_submit_response(nghttp2_session *session, int32_t stream_id,
  * :type:`nghttp2_on_frame_send_callback` or
  * :type:`nghttp2_on_frame_not_send_callback` is called.
  *
- * For server, trailer must be followed by response HEADERS or
- * response DATA.  The library does not check that response HEADERS
- * has already sent and if `nghttp2_submit_trailer()` is called before
- * any response HEADERS submission (usually by
- * `nghttp2_submit_response()`), the content of |nva| will be sent as
- * response headers, which will result in error.
+ * For server, trailer fields must follow response HEADERS or response
+ * DATA with END_STREAM flag set.  The library does not enforce this
+ * requirement, and applications should do this for themselves.  If
+ * `nghttp2_submit_trailer()` is called before any response HEADERS
+ * submission (usually by `nghttp2_submit_response()`), the content of
+ * |nva| will be sent as response headers, which will result in error.
  *
  * This function has the same effect with `nghttp2_submit_headers()`,
  * with flags = :enum:`NGHTTP2_FLAG_END_HEADERS` and both pri_spec and
  * stream_user_data to NULL.
  *
- * To submit trailer after `nghttp2_submit_response()` is called, the
- * application has to specify :type:`nghttp2_data_provider` to
- * `nghttp2_submit_response()`.  In side
- * :type:`nghttp2_data_source_read_callback`, when setting
+ * To submit trailer fields after `nghttp2_submit_response()` is
+ * called, the application has to specify
+ * :type:`nghttp2_data_provider` to `nghttp2_submit_response()`.  In
+ * side :type:`nghttp2_data_source_read_callback`, when setting
  * :enum:`NGHTTP2_DATA_FLAG_EOF`, also set
  * :enum:`NGHTTP2_DATA_FLAG_NO_END_STREAM`.  After that, the
- * application can send trailer using `nghttp2_submit_trailer()`.
- * `nghttp2_submit_trailer()` can be used inside
- * :type:`nghttp2_data_source_read_callback`.
+ * application can send trailer fields using
+ * `nghttp2_submit_trailer()`.  `nghttp2_submit_trailer()` can be used
+ * inside :type:`nghttp2_data_source_read_callback`.
  *
  * This function returns 0 if it succeeds and |stream_id| is -1.
  * Otherwise, this function returns 0 if it succeeds, or one of the