How to Add Extension of album files in folder names?

I use the "tag - filename " section and the following command for folder and classification:

new_dir\%albumartist% - %album% **(album format)**\$num(%track%,2). %title%

I want the format of the album to be mentioned in the folder name based on the extension of the files in the folder.
That is, by using the file extension, I should put a condition that in the section related to (album format) in folder name, whatever the extension of the files was, should be mentioned in the folder name, that is:
if the files were in the format of .m4a, the value of "itunes" should be placed,
if .mp3 were the value of MP3 and
if .flac were the value of FLAC should be placed.

Is there a method for this?

Several things:
could you please post in the forum section that is appropriate?
i do not think that the original choice "development/export" has anything to do with renaming folders.

Then, if you have text parts with special characters, please follow

esp. the part about the formatting.

And then there is the search function and I found with the keywords "folder name extension" this thread:

which features more or less the idea:

@ohrenkino
Yes, Sure
There is only one problem, I wanted to create the post in the " How to " section but this section is inactive for me. A message indicates that you are not allowed to create a topic in this section .
What is the reason for that? How can I create a post in " how to" the section?

Is there a way to add the value of (%_extension%) in Uppercase style to the folder name?

The HowTo section features threads an posts that tell you how to do things, not to ask how you do them. So at least this thread would not fall into that category. - support is the better section, I think.

Have a look at the documentation:

esp. $upper()
e.g. $upper(%_extension%)