"I'm trying to figure out for what task this data structure would be convenient"

Thanks for your reply.

For this case, I have a file with information formated as I've posted above.

This is:
1 to 5 digits, 1 space, 1 to 65 characters

Each line represents classes and subclasses (and sub-sub-classes...) and their names.
Each digit represents one level.

For example: 

11234 Some Text
      ^^^^^^^^^---- Name of this class (level)
    ^------- 5th class
   ^-------- 4th class
  ^--------- 3th class
 ^---------- 2nd class
^----------- Top (main class)

[download]

Classes' levels varies between 1 and 9.

I'm trying to use this Hash to create an XML document.

In reply to Re^2: Generation of a Hash of Hashes by Miguel
in thread Generation of a Hash of Hashes by Miguel

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