# Differences between the id3v2.3/4 standard and mp3tags implementation
**URL:** https://community.mp3tag.de/t/differences-between-the-id3v2-3-4-standard-and-mp3tags-implementation/68519
**Category:** Development
**Created:** [May 16, 2025, 6:29pm UTC](https://community.mp3tag.de/t/differences-between-the-id3v2-3-4-standard-and-mp3tags-implementation/68519 "2025-05-16T18:29:36Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@yorickausyps](https://community.mp3tag.de/u/yorickausyps)
#### Post date: [May 16, 2025, 6:29pm UTC](https://community.mp3tag.de/t/differences-between-the-id3v2-3-4-standard-and-mp3tags-implementation/68519/1 "2025-05-16T18:29:36Z")
During the development of scripts for the Discogs WS I found the following two points regarding the documentation and implementation of the id3-standard in mp3tag.
1. Mp3tag claimes in its documentation [https://docs.mp3tag.de/mapping/](https://docs.mp3tag.de/mapping/), that there exists a tag field named "GROUPING" in id3v2.3 and id3v2.4 with header GRP1. This frame can't be found in the id3-documents under [https://id3.org/Developer%20Information](https://id3.org/Developer%20Information). Perhaps this tag field only exists for matroska file format? In this case the mp3tag-documents should be corrected.
2. Similar to the "Copyright Message" TCOP frame the id3-documents define for id3v2.4 a "Produced Notice" TPRO frame, in which the string must begin with a year and a space character, followed by the production copyright holder of the original sound. Every time this field is displayed the field must be preceded with "Produced " (P) " ", where (P) is one character showing a P in a circle.This feature seems to be missing in mp3tag and I would like it to be added, so that I am able to make experiments with it.
---
### Author:  [@Doug\_Mackie](https://community.mp3tag.de/u/Doug_Mackie)
#### Post date: [May 16, 2025, 6:46pm UTC](https://community.mp3tag.de/t/differences-between-the-id3v2-3-4-standard-and-mp3tags-implementation/68519/2 "2025-05-16T18:46:57Z")
On your point #1, please see here for an explanation:
[Support for new iTunes Grouping id3 frame "GRP1"?](https://community.mp3tag.de/t/support-for-new-itunes-grouping-id3-frame-grp1/18523)
UPDATE: I suspect that your reference above to that [ID3.org](https://id3.org/Developer%20Information)
page is out of date. The [Hydrogen Audio mapping tables](https://wiki.hydrogenaud.io/index.php?title=Tag_Mapping#Mapping_Tables) do list GRP1 for Id3v2.3/4. Scroll down to the row for "Content Group".
On your suggestion for a "Produced Notice" TPRO frame for id3v2.4, I'll let others comment.
I never use id3v2.4.