What if the hard disk is partitioned into more than 26 sections in Windows?

The drive letters you see are simply representations of the physical partitions available and can be represented by other means. You could only have up to 26 drive letters, but you are definitely able to have (and actually use) many more partitions.

In that case, you could link the drive to a directory on your system rather than a drive letter as, since Windows XP at least (and potentially earlier), it has been possible to mount a drive or partition under a directory in Windows. This would mean you could effectively have a folder containing all your drives that are not accessible by drive letter.

You would do this within the Disk Management administrative console.

To get to the console, go to (or right-click on "My Computer" -> "Manage" -> "Disk Management"):

Start > Run and type
diskmgmt.msc

If you right click a partition you would see a Change Drive Letter or Path option which where you can add or remove paths or drive letters for drives.

As a side not you will want to make sure that the folder that you are using is empty, when you mount a partition to that folder then you will only see the files and folders from that partition and any original files will be invisible. I suspect if you unmount the drive from that folder you will be able to see the original files again, but I don't know for certain.

Weird, I assumed that there would be some kind of limit on how many logical partitions you can have in an extended partition, but I can't actually find anything about it. I know you can only have four primary partitions.

This is an example drive that I have removed the drive letter from and instead assigned to a folder, the files on that drive are now accessible at C:\Temp\Test and the drive no longer has a letter assigned to it:

Under DOS 3.3 at least you could get drives like [:\ i.e .the ASCII characters after Z.

This was using Novell and setting LASTDRIVE to some high letter.

So there might be a way of getting the 27th partition to have a character name.

Little-known undocumented feature: you can use any drive "letter" you want with the mountvol command. First, use mountvol undecorated to get a list of present volumes with their \\?\Volume{GUID}\ paths. Then, you can do something like this:

mountvol -: \\?\Volume{7d0832b2-3d3a-4fe0-9473-9f7aaabc5a98}\
-:

That - isn't a placeholder - it actually works as a drive identifier, and you can change your current drive in the command prompt to it, cd around, and do everything you'd expect to be able to do. As far as I can tell, every symbol except the space works.

Explorer won't let you browse in non-lettered drives, but you can open some programs on documents in them. notepad filename.ext works on the prompt from inside that drive, for instance. (But notepad -:\filename.ext doesn't work from the Run dialog.)