One reason why nobody has requested this yet may also be that this value is probably not put into practice very often. The vast majority of calculated album gain values is anyway in the negative dB regime which avoids clipping automatically. Still, because it's part of the standard now, I think it's better to have a full set of parameters and will definitely welcome it if MM upgrades to the new standard in a future release.

For the moment, I will follow your suggestion and tag according to the old standard, adding album peak values potentially later which should be a very simple operation. All in all, I would not like to change to another program for tagging because at my usage MM's tagging has proven quite stable across several applications what I can not say about some other tagging engines I used in the past.

[quote=joa08 post_id=482854 time=1623497423 user_id=113747]
Is there any special reason why MM does not use/store a value for replaygain_album_peak although it would be a valid parameter according to the ReplayGain standard? And additional question: Will I run into any problems if I use files without this value on programs other than MM?

I'm asking this because I'm currently about to generate ReplayGain parameters for my whole library which takes quite a while, and it would be interesting to know if the tagging is future safe when I'm finished or if I have to repeat the process all over sometime because the files are missing one important value.
[/quote]

The reason is, that it was not part of the standard in the past and nobody requested it yet. But we plan to [url=https://www.ventismedia.com/mantis/view.php?id=16492]add support for ReplayGain 2[/url] for 5.1 version, I have added it there, to not forget to add it. Thanks for noticing.
I think other apps should always use track peak value, if album peak is not present, it should not be problem. Once MM adds support for album peak value, it will probably automatically fill this value to database (it can be automatically filled from track peak values during database upgrade) and you can re-tag your files, if needed, it will be as fast as any simple tagging.
Also if this tag is already present in the file from some other software, MM preserves it and displays as extended tag (Properties - Custom).

Is there any special reason why MM does not use/store a value for replaygain_album_peak although it would be a valid parameter according to the ReplayGain standard? And additional question: Will I run into any problems if I use files without this value on programs other than MM?

I'm asking this because I'm currently about to generate ReplayGain parameters for my whole library which takes quite a while, and it would be interesting to know if the tagging is future safe when I'm finished or if I have to repeat the process all over sometime because the files are missing one important value.

As the linked table shows, MM uses standard tags for volume info - (RVA2, RGAD, TXXX:replaygain_track_gain, replaygain_track_peak, replaygain_album_gain). Because of inconsistencies in RVA2 format across tagging applications, MM saves volume info after analyzing only to RGAD and these 3 TXXX tags. So I guess, the other application simply did not show and did not remove this standard RGAD tag.

If you removed the file from the Library and it rescans with the a value show it likely means that either the tag editor didn't remove the value or that another tag exists with this value.

You can offer an unedited and an edited copy to Support via a fileshare like Dropbox (share link to it in Ticket): https://www.mediamonkey.com/support/index.php?/Tickets/Submit

Steps:
1. Change manually the track volume of a track inside MM to for example, -3db.
2. Remove the track from the library or PC.
3. In an external tag editor (TagScanner, for example), make the replaygain_track_gain tag empty that is -3db.
4. Rescan and import the track inside MM.
The track volume is still -3 db!

The mentioned option "automatically analyze volume of unanalyzed files" is not checked.
There is no other related tag shown in the external tag editor.

So you, removed the file from MediaMonkey, delete the volume related tags outside of MediaMonkey and then scanned the file into MediaMonkey? Then there may be other tags with this information in the file or you have the option to analyze files with unknown leveling value enabled.

It seems it's a bug. I have removed the emptied tags file, once from the library and once from the library and PC but the track volume field won't be updated in MM, when I rescan and import it.

Then you may have to remove the files from MediaMonkey and rescan them. In the past there have been issues with tags being emptied outside of MediaMonkey not updating on rescanning with the now empty value if MediaMonkey had a value for them.

Of course, if I change the value inside MM, it will be shown and updated in the external tag editor, but if I change/delete the value inside the external tag editor, the value won't be updated.

Did you rescan the files in MediaMonkey after you edited those tags?

As far as I have understood, the related tags for a MP3 file are:
replaygain_track_gain
replaygain_track_peak
replaygain_album_gain

But when I delete those tags by a tag editor, there will be still volume track value present in MediaMonkey. Please may you check it?

Yes (with default settings): https://www.mediamonkey.com/wiki/index.php?title=WebHelp:About_Track_Properties/4.0

Thanks!

Another question, is this tag stored in the file? Because I can't see any related tag when using a tag editor, like TagScanner?

Play > Level Playback Volume would stop using the value.

You can edit Track Volume (not Album Volume) inline (not in Properties) by using F2 on the field in the Tracklisting.