Add Signer UID and Unlocking for Impl Acc Cr Addr

tips/TIP-0042/tip-0042.md

@@ -956,6 +956,8 @@ Account Creation Address_ was derived.
 Thus, since implicit accounts are much easier to create than a regular account, and are sufficient to create a full
 account from, without having to rely on a third party, the barrier to entry for the network is lowered.
 
+### Implicit Account Creation Address
+
 The following table shows the mapping from the address type of the **first byte** to the address type:
 
 | Address                           | Type Byte as `uint8` | Bech32 Encoded |
@@ -995,7 +997,18 @@ The following table shows the serialization of an _Implicit Account Creation Add
 An _Implicit Account Creation Address_ is structurally the same as an _Ed25519 Address_, except for the _Address Type_,
 and thus also backed by an Ed25519 key pair.
 
-### Storage Score
+#### Signer UID
+
+The Signer UID of an _Implicit Account Creation Address_ is the `Pub Key Hash`.
+
+#### Unlocking
+
+The address `Address` in a given input at index `Input Index` is unlocked in a transaction if and only if:
+
+- The `Unlock` in `Unlocks` at `Input Index` is a semantically valid _Unlock_ and is itself or points to a _Signature
+  Unlock_ whose _Signer UID_ matches the _Signer UID_ of the `Address`.
+
+#### Storage Score
 
 - The storage deposit of an _Implicit Account Creation Address_ defines a dedicated Storage Score Offset:
   `Storage Score Offset Implicit Account Creation Address`. It is designed to match the Storage Score required for a