fix descriptions of msg_type and extension_type on framing_sv2 docs..

for more details see stratum-mining/sv2-spec#117

protocols/v2/framing-sv2/README.md

@@ -14,13 +14,23 @@ type, message type, and message length (six bytes in total), followed by a varia
 message. The message framing is outlined below ([according to Sv2 specs
 ](https://github.com/stratum-mining/sv2-spec/blob/main/03-Protocol-Overview.md#32-framing)):
 
-| Protocol Type  | Byte Length | Description |
+| Field Name  | Byte Length | Description |
 |----------------|-------------|-------------|
-| `extension_type` | `U16` | Unique identifier of the extension describing this protocol message. <br><br> Most significant bit (i.e.bit `15`, `0`-indexed, aka `channel_msg`) indicates a message which is specific to a channel, whereas if the most significant bit is unset, the message is to be interpreted by the immediate receiving device. <br><br> Note that the `channel_msg` bit is ignored in the extension lookup, i.e.an `extension_type` of `0x8ABC` is for the same "extension" as `0x0ABC`. <br><br> If the `channel_msg` bit is set, the first four bytes of the payload field is a `U32` representing the `channel_id` this message is destined for (these bytes are repeated in the message framing descriptions below). <br><br> Note that for the Job Declaration and Template Distribution Protocols the `channel_msg` bit is always unset. |
-| `msg_type` | `U8` | Unique identifier of the extension describing this protocol message. |
+| `extension_type` | `U16` | Unique identifier of the extension associated with this protocol message. |
+| `msg_type` | `U8` | Unique identifier of this protocol message. |
 | `msg_length` | `U24` | Length of the protocol message, not including this header. |
 | `payload` | `BYTES` | Message-specific payload of length `msg_length`. If the MSB in `extension_type` (the `channel_msg` bit) is set the first four bytes are defined as a `U32` `"channel_id"`, though this definition is repeated in the message definitions below and these 4 bytes are included in `msg_length`. |
 
+Some bits of the `extension_type` field can also be repurposed for signaling on how the frame should be handled across channels.
+
+The least significant bit of `extension_type` (i.e.bit 15, 0-indexed, aka `channel_msg`) indicates a message which is specific to a channel, whereas if the most significant bit is unset, the message is to be interpreted by the immediate receiving device.
+
+Note that the `channel_msg` bit is ignored in the extension lookup, i.e.an `extension_type` of `0x8ABC` is for the same "extension" as `0x0ABC`.
+
+If the `channel_msg` bit is set, the first four bytes of the payload field is a `U32` representing the `channel_id` this message is destined for (these bytes are repeated in the message framing descriptions below).
+
+Note that for the Job Declaration and Template Distribution Protocols the `channel_msg` bit is always unset.
+
 ## Main Components
 
 - **Header**: Defines the 6-byte Sv2 message header with information about the message payload,

protocols/v2/framing-sv2/src/lib.rs

@@ -12,10 +12,10 @@
 //! The message framing is outlined below ([according to Sv2 specs
 //! ](https://stratumprotocol.org/specification/03-Protocol-Overview/#32-framing)):
 //!
-//! | Protocol Type  | Byte Length | Description |
+//! | Field Name | Byte Length | Description |
 //! |----------------|-------------|-------------|
-//! | `extension_type` | `U16` | Unique identifier of the extension describing this protocol message. <br><br> Most significant bit (i.e.bit `15`, `0`-indexed, aka `channel_msg`) indicates a message which is specific to a channel, whereas if the most significant bit is unset, the message is to be interpreted by the immediate receiving device. <br><br> Note that the `channel_msg` bit is ignored in the extension lookup, i.e.an `extension_type` of `0x8ABC` is for the same "extension" as `0x0ABC`. <br><br> If the `channel_msg` bit is set, the first four bytes of the payload field is a `U32` representing the `channel_id` this message is destined for (these bytes are repeated in the message framing descriptions below). <br><br> Note that for the Job Declaration and Template Distribution Protocols the `channel_msg` bit is always unset. |
-//! | `msg_type` | `U8` | Unique identifier of the extension describing this protocol message. |
+//! | `extension_type` | `U16` | Unique identifier of the extension associated with this protocol message. |
+//! | `msg_type` | `U8` | Unique identifier of this protocol message. |
 //! | `msg_length` | `U24` | Length of the protocol message, not including this header. |
 //! | `payload` | `BYTES` | Message-specific payload of length `msg_length`. If the MSB in `extension_type` (the `channel_msg` bit) is set the first four bytes are defined as a `U32` `"channel_id"`, though this definition is repeated in the message definitions below and these 4 bytes are included in `msg_length`. |
 //!