If you're on a NetBSD mirror, after traversing into the tree you'll see various directories that seem to do the same.

You have to traverse the directories of a NetBSD server (ftp.netbsd.org might be the best one, as it is the reference), find out which directories have which meaning, and document that. In the end, you should think about a good ASCII representation of a directory tree and realize it.

Our preferred format for the submission is some form of plain text, as that is most portable and can be read anywhere.  If you want to use a word processor, please export the file as text.  You could also add something like markdown or latex to add structure (these are both plain text based), but that is not a requirement.