hmm it sounds like you're asking if there is any way to query different levels in a nested field...
Your specific request requires two things...
1. Be able to refer to a particular level in a nested field for use in expressions, views and rename functions
For example, how can I output "Level B" in a Level A\Level B expression? Maybe something like =[Field]!2 or similar to refer to the second level. We don't have anything like this yet
We did ask about this, but I don't think there's a way at the moment. Maybe someone who knows a bit more about mid expressions than I do can help.
2. To achieve what you want, using nested fields, you need to output the second level into an expression or view, BUT only if the the first level equals X
That's another level of complexity... we have IF functions to work with in MC, but without a way to refer to one level or another in a nested field, this won't help you at the moment.
The ideal solution for your problem would be a relational database, where files could belong to multiple database entries and be tagged with separate tracks etc accordingly... but we're not there yet... So hope for a new expression logic, but in the mean time, you might be stuck keeping those multiples copies of the same file like the rest of us
Someone jump in if I've missed something big here...
Edit: Sorry, are you talking about setting up your nested panes, or querying the data once it's done?
To set up the field to be nested, just use \ to separate your levels.
How is your chart data stored currently? Is it in another field? Or are you entering it manually?
If the track numbers are stored in another field somewhere, you can save a bit of time...
Eg say you have tracks tagged in the form "Billboard 2005 No. 4" in a custom field [Charts]
To copy it to the KW field and nest it... ie Billboard 2005\4 etc
1. Select the files you're tagging
2. Move/Copy Fields [Charts] to [Keywords]
3. Find & Replace (select Charts) " No. " with "\" (don't use the apostrophes)
The last one turns it into a nested field
As far as querying/returning a level elsewhere (ie "Billboard 2005" or "4" in the above example), see above