Well, having had more thinking about it, I found a solution. As I thought, it involves more than one step, but when you have created all the action groups, it works with a few key shortcuts.
Step 1:
Get my web sources sript for discogs: /t/9226/1
When you are at step 6 of the "installation" described there, it is important that you change DISCOGS_TOTALTRACKS from "no" to "totaltracks" (or however you want to call it, but you must have that field written).
Step 2:
Tag your incomplete albums with my script. At the "adjust tag information" window in the web source process, move the < no association > lines to the missing tracks.
Step 3:
The first action group:
Action 1: Format Value
Field: _FILENAME
Formatstring: %track% - - - TRACK IS MISSING - - -.mp3\%_filename%
Action 2: Format Value
Field: _FILENAME
Formatstring: .\%_filename%
Action 3: Export
Export File Name: $if($geql(%totaltracks%,1),1 - - - TRACK IS MISSING - - -.mp3,$getenv(appdata)\Mp3tag\dummy file.txt)
Export File Code: $filename($if($geql(%totaltracks%,1),1 - - - TRACK IS MISSING - - -.mp3,$getenv(appdata)\Mp3tag\dummy file.txt),ansi)
Action 4: Export
Export File Name: $if($geql(%totaltracks%,2),2 - - - TRACK IS MISSING - - -.mp3,$getenv(appdata)\Mp3tag\dummy file.txt)
Export File Code: $filename($if($geql(%totaltracks%,2),2 - - - TRACK IS MISSING - - -.mp3,$getenv(appdata)\Mp3tag\dummy file.txt),ansi)
Action 5: Export
Export File Name: $if($geql(%totaltracks%,3),3 - - - TRACK IS MISSING - - -.mp3,$getenv(appdata)\Mp3tag\dummy file.txt)
Export File Code: $filename($if($geql(%totaltracks%,3),3 - - - TRACK IS MISSING - - -.mp3,$getenv(appdata)\Mp3tag\dummy file.txt),ansi)
Actions 6 - ???:
Repeat this export as many times as you think the maximal tracknumber of a release could be. I would reccomend about 50 or 60 times to be able to deal with 2CD releases. Only change number on the positions i marked in blue print. Change the number in such a way, that it counts from 1 to ???, each Export represents one tracknumber. The mte file for the the export only needs one line as showed above.
last Action: Format Value
Field: _FILENAME
Formatstring: %track% - - - TRACK IS MISSING - - -.mp3\%_filename%
After that action you get a error message from Mp3tag which says, that the "x - - - TRACK IS MISSING - - -.mp3" file could not be created for every track that is there. That is intentional and the idea my solution builds on. The creation is prevented by the existence of the folder with the same name.
$getenv(appdata) can only be used if you have Mp3tag v2.48a or newer. If you use a older version (as your profile says) and do not want to update, you have to replace this by the path to you application date folder (which is C:\Users<user name>\AppData\Roaming) at my Windos Vista. At this place a little dummy file.txt file gets written for every tracknumbe which is higher than TOTALTRACKS. Only one file is written and overwritten everytime you use this action group. So you don't have to care about deleting it.
Step 4:
The second action group:
Action: Format Value
Field: _DIRECTORY
Formatstring: .\
Now you have dummy mp3 files for every missing track. When you are happy without further artist and title information, you don't have to go through the last two steps. In this case, you might als like a different file ending at this point. If so, replace all instances of "mp3" in orange print above with "missing" (or whatever you like).
Step 5:
Press F5 to refresh the folder and see the new dummy mp3 files.
Use my web sources script again to tag the dummy mp3 file. (you don't have to search this time at discogs, choose the direct by ID or direct by URL script)
Step 6:
The third action group:
Action 1: Format Value
Field: _FILENAME
Formatstring: (%discogs_catalog%) (%album%) $num(%track%,2) - %artist% - %title%$if($eql($right(%_filename%,29), - - - TRACK IS MISSING - - -), - - - TRACK IS MISSING - - -,)
Action 2: Regular Expression
Field: _FILENAME
Regular Expression: (.+) - - - TRACK IS MISSING - - -.mp3
Replace Matches With: $1.missing
As you see I have take you formatstring here. You can change that part in purple print to whatever you like. The important part comes in the $if function afterwards.
And of course you could also leave away Action 3 of Step 6 if you want to see the dummy representators of the missing files in you media library. In this case I would recommend you a action wich puts a MISSING in capital letters after the trackname for not loosing the overview in your collection over what is there and what is missing.
As I have have already created the action groups to thest this, I attach them to this post. Put the mta file inside the Mp3tag/data/actions folder and the mte files inside of Mp3tag/export. I have made only six exports at the first action group for testing. You will have to copy and change the other yourself.
create_dummy_file_for_missing_tracks.zip (2.25 KB)