TIP-23 Tagged Data Payload (#54)

* add tip-23

* Update tip-0023.md

* Update tip-0023.md

* Update dynamic bytearray defs (#25)

* Update with "Message" to "Block" renaming to align with IOTA 2.0 terminology

Co-authored-by: Levente Pap <levente.pap@iota.org>

tips/TIP-0023/tip-0023.md

@@ -0,0 +1,46 @@
+---
+tip: 23
+title: Tagged Data Payload
+description: Block payload for arbitrary data
+author: Wolfgang Welz (@Wollac) <wolfgang.welz@iota.org>
+discussions-to: https://github.com/iotaledger/tips/pull/54
+status: Draft
+type: Standards
+layer: Core
+created: 2022-01-24
+---
+
+# Abstract
+
+The payload concept offers a very flexible way to combine and encapsulate information in the IOTA protocol. This document proposes a basic payload type that allows the addition of arbitrary data.
+
+# Motivation
+
+The most flexible way to extend an existing object is by the addition of arbitrary data. This payload provides a way to do just that. An optional tag can be used to categorize the data.
+
+# Specification
+
+## Serialized Layout
+
+The following table describes the serialization of a _Tagged Data Payload_ following the notation from [TIP-21](../TIP-0021/tip-0021.md):
+
+| Name         | Type              | Description                                              |
+|--------------|-------------------|----------------------------------------------------------|
+| Payload Type | uint32            | Set to *value 5* to denote an _Tagged Data Payload_.     |
+| Tag          | (uint8)ByteArray  | The tag of the data. A leading uint8 denotes its length. |
+| Data         | (uint32)ByteArray | Binary data. A leading uint32 denotes its length.        |
+
+It is important to note that `Tag` is not considered by the protocol, it just serves as a marker for second layer applications.
+
+## Syntactic Validation
+
+- `length(Tag)` must not be larger than [`Max Tag Length`](../TIP-0022/tip-0022.md).
+- Given the type and length information, the _Tagged Data Payload_ must consume the entire byte array of the `Payload` field of the encapsulating object.
+
+# Rationale
+
+As the tag is not considered by the protocol, it could also be removed completely. However, Legacy IOTA and Chrysalis supported sending of arbitrary data indexed with a tag. Thus, in order to simplify the migration of second layer applications using these protocols, the optional `Tag` has been added which can be used in a similar manner.
+
+# Copyright
+
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).