REQUEST: predefined disc field

I would like to suggest expanding current ability to pre-define tag fields with values chosen by the user

Right now in
Tools > Options > Genres
we can add our own genres, so that they form a ready to use list

The same could be done for a field like a DISCNUMBER. But it is not a default [basic] field displayed in the Tag Panel, so adding such an option just for this one would be only a half step forward. Such ability should be expanded to the full extent: every field should be definable with user chosen values

The DISCNUMBER is the one I would use in such a way, defining it to my likening
1 / 2
1 / 3
1 / 4
2 / 2
2 / 3
2 / 4
3 / 3
3 / 4
4 / 4
which would cover something like 99% of cases [albums] and at the same time making the choosing a quick decision [based on only 9 entries]. Of course listing and using those values should not make impossible adding other by keyboard input [that 1% cases, something rare like "8 / 8"]

And that already existing Genres could be retained in lets say
Tools > Options > Pre-Defined > Genres
as an example

It may seems that this is too much. That besides GENRE and DISCNUMBER no one will use this for fields like TITLE or COMPOSER. And that's probably true. But it could be also used for some tag field bearing a rating of a song or something like source of recording [a field listing digital, CD, DVD, tape, vinyl

The alternative / workaround to this is of course using of user defined actions. But having many of them requires from me scrolling down the list, which takes time. So if my change would be implemented, I could make list of my actions shorter by moving some stuff from it to Tag Panel, thus saving some time and space

Please note that the names of Genres is pre-defined by the ID3V1 standard which maps 2 bytes to string constants.
You see a table of these pre-defined values e.g. in wikipedia:

https://de.wikipedia.org/wiki/Liste_der_ID3v1-Genres

On the disc number topic, see e.g. this thread:
/t/12096/1

But the fact that they are predefined doesn't stop us from the making our own list. That's what the already existing
Tools > Options > Genres
is for, isn't it?

So I'm proposing to extend such ability to all of the other fields

That is a big workaround that doesn't really touch the subject

First: putting in a systematic way additional info that in the first place can be stored in tag field other than TITLE, is just taking away a precious space from FILENAME; which is a complex problem if the modus operandi [like that of mine] aims at having the same values in TITLE and FILENAME. Because the root problem with FILENAME is that it's length is limited and that leads to rare but very problematic issues with very long TITLEs that differentiate only at their end, once there are in the same folder. I may have two different tracks entitled in the TITLE field

The Contest Between Harmony And Invention, The Four Seasons, Opus #8, Concerto #1 In E Major (Spring), RV #269, Movement 1: Allegro

The Contest Between Harmony And Invention, The Four Seasons, Opus #8, Concerto #1 In E Major (Spring), RV #269, Movement 3: Allegro Pastorale

but I have to somohow shorten them and at the same time differentiate in their FILENAME, especially if I want to burn them on a optical disc. [And yes, putting a disc / track number in front of titles would take that issue away, but would also bring it back if there was no ALBUM and thus DISC / TRACK values to copy]

And second [and more importantly]: what I wish for is to have a choice for all values [tag fields] to either put them down via actions or choose them from the predefined list. Just like I can to it now only for the GENRE tag. That functionality is already there, but limited to only one tag field

There have been a few threads on this topic. Has been on a wishlist for a while. There was some reason for its lack of implementation (complexity?), can't recall.

If you frequently tag audio books then 8/8 is much more the rule than the exception. So as you claim why certain workarounds are not suitable for you, this would not prove to be a real improvement for different workflows and environments.

The real improvement would be a discnumber assistant like the track numbering wizard.
User-defined values should be dealt with in user-defined actions.

You've got a point there