Governance updates

- Add description of govsync to P2P guide
 - Updates to P2P reference

_includes/devdoc/guide_p2p_network.md

@@ -587,3 +587,46 @@ Take note that for both types of broadcasting, mechanisms are in place to punish
 Earlier versions of Bitcoin Core allowed developers and trusted community members to issue [Bitcoin alerts](https://bitcoin.org/en/alerts) to notify users of critical network-wide issues. This messaging system [was retired](https://bitcoin.org/en/alert/2016-11-01-alert-retirement) in Bitcoin Core v0.13.0; however, internal alerts, partition detection warnings and the `-alertnotify` option features remain.
 
 {% endautocrossref %}
+
+
+
+### Governance
+
+{% include helpers/subhead-links.md %}
+
+{% autocrossref %}
+
+#### Synchronization
+
+Dash Core synchronizes the governance system via the Masternode network as the
+last stage of the Masternode sync process (following they sync of sporks, the
+Masternode list, and Masternode payments).
+
+The `govsync` message initiates a sync of the governance system. Masternodes
+respond to the `govsync` message with several items:
+
+* First, the Masternode sends one `ssc` message (Sync Status Count) for `govobj`
+objects and one for `govobjvote` objects. These messages indicates how many
+inventory items will be sent.
+
+* Second, the Masternode sends `inv` messages for the `govobj` and `govobjvote`
+objects.
+
+Once the syncing node receives the counts and inventories, it may request any
+`govobj` and `govobjvote` objects from the Masternode via a `getdata` message.
+
+*Governance Sync Data Flow*
+
+| **Syncing Node Message** | **Direction**  | **Masternode Response**   | **Description** |
+| `govsync`                | →              |                           | Syncing node initiates governance sync
+|                          | ←              | `ssc` message (govobj)    | Number of governance objects
+|                          | ←              | `ssc` message (govobjvote)| Number of governance object votes
+|                          | ←              | `inv` message (govobj)    | Governance object inventories
+|                          | ←              | `inv` message (govobjvote)| Governance object vote inventories
+| `getdata` (govobj)       | →              |                           | (Optional) Syncing node requests govobj
+|                          | ←              | `govobj` message          | (If requested) Governance object
+| `getdata` (govobjvote)   | →              |                           | (Optional) Syncing node requests govobjvote
+|                          | ←              | `govobjvote` message      | (If requested) Governance object vote
+
+
+{% endautocrossref %}

_includes/devdoc/ref_p2p_networking.md

@@ -2230,15 +2230,24 @@ contract, or setting.
 
 | Bytes | Name | Data type | Required | Description |
 | ---------- | ----------- | --------- | -------- | -------- |
-| 32 | nHashParent | uint256 | Required | Parent object, 0 is root
+| 32 | nHashParent | uint256 | Required | Parent object (a hash of all zeros here indicates this is the root object, not a child object).
 | 4 | nRevision | int | Required | Object revision in the system
 | 8 | nTime | int64_t | Required | Time which this object was created
 | 32 | nCollateralHash | uint256 | Required | Hash of the collateral fee transaction
 | 0-16384 | strData | string | Required | Data field - can be used for anything (leading varint indicates size of data)
-| 4 | nObjectType | int | Required | Type of governance object as defined by src/governance-object.h
+| 4 | nObjectType | int | Required | Type of governance object: <br>• `0` - Unknown<br>• `1` - Proposal<br>• `2` - Trigger<br>• `3` - Watchdog
 | 41 | vinMasternode | CTxIn | Required | Unspent output for the masternode which is signing this object
 | 66* | vchSig | char[] | Required | Signature of the masternode (66 bytes in most cases. Length (1 byte) + Signature (65 bytes))
 
+Governance Object Types (defined by src/governance-object.h)
+
+| Object Type | Description
+|------|--------------
+| 0 | GOVERNANCE_OBJECT_UNKNOWN
+| 1 | GOVERNANCE_OBJECT_PROPOSAL
+| 2 | GOVERNANCE_OBJECT_TRIGGER
+| 3 | GOVERNANCE_OBJECT_WATCHDOG
+
 The following annotated hexdump shows a `govobj` message. (The
 message header has been omitted.)
 
@@ -2327,13 +2336,16 @@ dc45e9c09ee0427223e332b52e8d709e
 
 {% autocrossref %}
 
-The `govsync` message is used to request syncing of governance objects with peers.
+The `govsync` message is used to request syncing of governance objects
+(`govobj` message and `govobjvote` message) with peers.
 
 | Bytes | Name | Data type | Required | Description |
 | ---------- | ----------- | --------- | -------- | -------- |
 | 32 | nHash | uint256 | Required |
 | # | filter | CBloomFiter | Required |
 
+Note: Both the hash and bloom filter fields can be set to all zeros.
+
 The following annotated hexdump shows a `govsync` message. (The
 message header has been omitted.)