Add missing top-level Block syntactic validation

tips/TIP-0046/tip-0046.md

@@ -288,6 +288,29 @@ steps:
 
 The string format of the Block ID is the hexadecimal encoding of the `Block ID` with a `0x` prefix.
 
+## Syntactic validation
+
+The Tangle can only contain syntactically valid blocks. Invalid blocks must be rejected by the node. A Block is
+syntactically valid only if all of the following conditions hold:
+
+- The serialized size of the block does not exceed `32768`.
+- The `Protocol Version` in the `Header` matches the `Version` in the used protocol parameters.
+- The `Network ID` in the `Header` matches the `Network ID` from the protocol parameters, which is computed as described
+  in [TIP-45 (Network ID)](../TIP-0045/tip-0045.md#network-id).
+- Let `Commitment Slot` be the slot index to which the block commits, which can be extracted from the header's
+  `Slot Commitment ID`.
+- Let `Block Slot` be the slot index corresponding to the block header's `Issuing Time`.
+- If `Commitment Slot > Genesis Slot`, then it must hold that `Commitment Slot + Min Committable Age <= Block Slot`.
+  - Note: This ensures that the commitment is not too recent, except when committing to genesis.
+- It must hold that `Commitment Slot + Max Committable Age >= Block Slot`.
+  - Note: This ensures that the commitment is not too old.
+- The contained `Body` is syntactically valid.
+- There must be no trailing bytes after all block fields have been parsed.
+
+## Semantic Validation
+
+A _Block_ is semantically valid if the `Body`'s semantic validation passes.
+
 ## Basic Block
 
 ### Schema
@@ -442,11 +465,9 @@ A _Basic Block_ is the name for a _Block_ with its body set to a _Basic Block Bo
 
 ### Syntactic validation
 
-The Tangle can only contain syntactically valid blocks. Invalid blocks must be rejected by the node. A _Basic Block_ is
-syntactically valid if all of the following conditions hold:
+A _Basic Block Body_ is only syntactically valid if all of the following conditions hold:
 
 - The block adheres to its schema with the rules defined in [TIP-21](../TIP-0021/tip-0021.md).
-- The total length of the serialized block must not exceed `32768`.
 - It must hold true that 1 ≤ `Strong Parents Count` ≤ 8.
 - It must hold true that 0 ≤ `Weak Parents Count` ≤ 8.
 - It must hold true that 0 ≤ `Shallow Like Parents Count` ≤ 8.
@@ -455,7 +476,6 @@ syntactically valid if all of the following conditions hold:
   - must not have duplicates in each list.
 - `Weak Parents` must be disjoint from the rest of the parents: No weak parent should be in either `Strong Parents` or
   `Shallow Like Parents`.
-- There must be no trailing bytes after all block fields have been parsed.
 - If a _Basic Block_ contains a transaction payload, the block is valid only if all of the following conditions hold:
   - The Slot Index `Block Slot` corresponding to the `Issuing Time` of a block must be greater or equal than the
     `Creation Slot` of the contained transaction.
@@ -465,7 +485,7 @@ syntactically valid if all of the following conditions hold:
 
 ### Semantic Validation
 
-A _Basic Block_ is semantically valid if the following condition holds:
+A _Basic Block Body_ is semantically valid if the following condition holds:
 
 - The `Signature` must pass semantic validation.
 
@@ -638,11 +658,9 @@ A _Validation Block_ is the name for a _Block_ with its body set to a _Validatio
 
 ### Syntactic Validation
 
-The Tangle can only contain syntactically valid blocks. Invalid blocks must be rejected by the node. A _Validation
-Block_ is syntactically valid if all of the following conditions hold:
+A _Validation Block Body_ is only syntactically valid if all of the following conditions hold:
 
 - The block adheres to its schema with the rules defined in [TIP-21](../TIP-0021/tip-0021.md).
-- The total length of the serialized block must not exceed `32768`.
 - It must hold true that 1 ≤ `Strong Parents Count` ≤ 50.
 - It must hold true that 0 ≤ `Weak Parents Count` ≤ 50.
 - It must hold true that 0 ≤ `Shallow Like Parents Count` ≤ 50.
@@ -652,11 +670,10 @@ Block_ is syntactically valid if all of the following conditions hold:
 - `Weak Parents` must be disjoint from the rest of the parents: No weak parent should be in either `Strong Parents` or
   `Shallow Like Parents`.
 - `Highest Supported Version` must be greater or equal to `Protocol Version`.
-- There must be no trailing bytes after all block fields have been parsed.
 
 ### Semantic Validation
 
-A _Validation Block_ is semantically valid if the following condition holds:
+A _Validation Block Body_ is semantically valid if the following condition holds:
 
 - The `Signature` must pass semantic validation.