Integers

draft-ietf-quic-transport.md

@@ -2069,9 +2069,10 @@ The frame is as follows:
 The fields in the MAX_STREAM_ID frame are as follows:
 
 Maximum Stream ID:
-
-: ID of the maximum peer-initiated stream ID for the connection encoded as a
-  variable-length integer.
+: ID of the maximum unidirectional or bidirectional peer-initiated stream ID for
+  the connection encoded as a variable-length integer. The limit applies to
+  unidirectional steams if the second least signification bit of the stream ID
+  is 1, and applies to bidirectional streams if it is 0.
 
 Loss or reordering can mean that a MAX_STREAM_ID frame can be received which
 states a lower stream limit than the client has previously received.
@@ -2738,12 +2739,36 @@ for some applications.
 ## Stream Identifiers {#stream-id}
 
 Streams are identified by an unsigned 62-bit integer, referred to as the Stream
-ID.  To avoid Stream ID collision, clients MUST initiate streams using
-odd-numbered Stream IDs; servers MUST initiate streams using even-numbered
-Stream IDs. If an endpoint receives a frame which corresponds to a stream which
-is allocated to it (i.e., odd-numbered for the client or even-numbered for the
-server) but which it has not yet created, it MUST close the connection with
-error code STREAM_STATE_ERROR.
+ID.  The least significant two bits of the Stream ID are used to identify the
+type of stream (unidirectional or bidirectional) and the initiator of the
+stream.
+
+The least significant bit (0x1) of the Stream ID identifies the initiator of the
+stream.  Clients initiate even-numbered streams (those with the least
+significant bit set to 0); servers initiate even-numbered streams (with the bit
+set to 1).  Separation of the stream identifiers ensures that client and server
+are able to open streams without the latency imposed by negotiating for an
+identifier.
+
+If an endpoint receives a frame for a stream that it expects to initiate (i.e.,
+odd-numbered for the client or even-numbered for the server), but which it has
+not yet opened, it MUST close the connection with error code STREAM_STATE_ERROR.
+
+The second least significant bit (0x2) of the Stream ID differentiates between
+unidirectional streams and bidirectional streams. Unidirectional streams always
+have this bit set to 1 and bidirectional streams have this bit set to 0.
+
+The two type bits from a Stream ID therefore identify streams as summarized in
+{{stream-id-types}}.
+
+| Low Bits | Stream Type                      |
+|:---------|:---------------------------------|
+| 0x0      | Client-Initiated, Bidirectional  |
+| 0x1      | Server-Initiated, Bidirectional  |
+| 0x2      | Client-Initiated, Unidirectional |
+| 0x3      | Server-Initiated, Unidirectional |
+{: #stream-id-types title="Stream ID Types"}
+>>>>>>> origin/master
 
 Stream ID 0 (0x0) is a client-initiated, bidirectional stream that is used for
 the cryptographic handshake.  Stream 0 MUST NOT be used for application data.