Looking for opinions regarding track numbering

With the exception of some Apple formats, which do not allow leading zeros, all my tags have leading zeros for tracks 1-9 (01-09). However, regardless of the file type, my file names always have leading zeros, so whatever OS/Player or other software sees them in the correct order.

I have some compilations that consist of multiple discs, and I typically remove the disc numbers and make them one giant album, as many of the online databases (Amazon, Discogs, etc.) do this.
Because of this, I have a few compilations that contain over 100+ tracks.

So, my question is, how would you format the track numbers for albums that have more than 100 tracks? Would you leave tracks 1-99 as "01-99", or would you add an extra 0, making it "001-099"?

In the file names I would pad the track number to three digits.

However, in the track number fields, I've never found a need for leading zeros. Every device and every application that I've ever used interprets this field as numeric, so there's been no need.

The id3 specification says about TRCK:

Never heard about a 'numeric string'. It is numeric OR a string. But I think, they mean "a number followed by a slash followed by a number as one string".

I vote for "001/999".

That would have to be the ID3v2 spec, because the track number in ID3v1.1 is one byte and can only be interpreted as an unsigned integer from 0 to 255.

You are right, JJ Johnson. I forgot the url: http://id3.org/id3v2.3.0 (search for TRCK in the text, the search function on the page doesn't seem to work).

I would interpret this in the following way: the field requires a number (= numeric) and not other letters (so it is not "alphanumeric") except the slash to separate the totaltracks number.
The contents of the field is then supposed to be treated like a number - you can see that in MP3tag in the column definition as you have to tick "numeric" to get proper results for sorting.
And the $num() function (apparently) also only looks at the first part up to the slash